{"id":267915,"date":"2023-11-29T09:00:00","date_gmt":"2023-11-29T08:00:00","guid":{"rendered":"https:\/\/sherpas.com\/blog\/?p=267915"},"modified":"2023-11-24T16:33:03","modified_gmt":"2023-11-24T15:33:03","slug":"composition-air","status":"publish","type":"post","link":"https:\/\/sherpas.com\/blog\/composition-air\/","title":{"rendered":"La composition de l\u2019air : fiche de physique-chimie \ud83d\udca8"},"content":{"rendered":"\n<p>As-tu d\u00e9j\u00e0 r\u00e9fl\u00e9chi \u00e0 ce que tu respires\u202f? Chaque jour, on inhale et exhale de l&rsquo;air, un \u00e9l\u00e9ment essentiel \u00e0 notre survie, qu\u2019on peine cependant \u00e0 d\u00e9finir clairement dans une copie de physique-chimie. Comment en parler\u202f? Quels sont ses composants\u202f? Pourquoi est-il \u00e9tudi\u00e9 au coll\u00e8ge\u202f? <strong>Aujourd\u2019hui, on te dit tout sur la composition de l\u2019air<\/strong>. Pr\u00eat ? C\u2019est parti !\u200b \ud83d\ude80<\/p>\n\n\n<section class=\"relance\">\n        <div >\n                            <a target=\"_blank\" href=\"https:\/\/sherpas.com\/cours\/toute-matiere\/france\/college\">\n                    <div class=\"relance__container\"\n                        >\n                        \n                                                        <picture>\n                            <source srcset=\"https:\/\/sherpas.com\/content\/uploads\/2021\/12\/prendre-des-cours-particuliers-scaled.jpg\" media=\"(min-width: 999px)\">\n                            <source srcset=\"https:\/\/sherpas.com\/content\/uploads\/2021\/12\/prendre-des-cours-particuliers-scaled.jpg\" media=\"(max-width: 999px)\">\n                                <img decoding=\"async\"\n                                    src=\"https:\/\/sherpas.com\/content\/uploads\/2021\/12\/prendre-des-cours-particuliers-scaled.jpg\"\n                                    alt=\"prendre des cours particuliers\"\n                                >\n                            <\/picture>\n                                                <div class=\"relance__content\">\n                            \n                                <div class=\"relance__title\"> <p>Tu es au coll\u00e8ge et tu as besoin d&rsquo;aide dans une mati\u00e8re ? Prends des cours particuliers et d\u00e9croche les notes de tes r\u00eaves !<\/p>\n<\/div>\n                                                        <button type=\"button\"\n                                    class=\"relance__button btn btn-white\">\n                                Cartonne en cours \u200b\ud83d\udd25\n                            <\/button>\n                        <\/div>\n                    <\/div>\n                <\/a>\n                    <\/div>\n    <\/section>\n\n    \n\n\n<h2 class=\"wp-block-heading\" id=\"lair-cest-quoi-exactement\">L\u2019air, c\u2019est quoi exactement ?\u200b \ud83e\udd14<\/h2>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"piqure-de-rappel\">Piq\u00fbre de rappel \u200b\ud83e\uddd1\u200d\ud83c\udfeb<\/h3>\n\n\n\n<p>\u00ab L\u2019air, ben\u2026 c\u2019est le vide autour de nous \u00bb. Bien tent\u00e9, mais cette r\u00e9ponse ne fera pas mouche aupr\u00e8s de ton prof. <strong>Ce n\u2019est pas parce que tu ne vois pas une chose qu\u2019elle n\u2019existe pas<\/strong>. Personne ne peut entendre tes pens\u00e9es, et pourtant, elles sont r\u00e9elles !\u200b \ud83d\ude0e<\/p>\n\n\n<section class=\"you-know\">\n                <div class=\"you-know__title\"><p>\u200b\ud83d\udd0e D\u00e9finition<\/p>\n<\/div>\n                        <div class=\"you-know__text\">\n            <p>En physique-chimie, le terme \u00ab air \u00bb renvoie \u00e0 <strong>un fluide gazeux incolore, inodore et invisible<\/strong>. Il ne s\u2019agit ni d\u2019une mati\u00e8re liquide, ni d\u2019une mati\u00e8re solide. Ce n\u2019est pas non plus un corps pur puisque<strong> l\u2019air est un m\u00e9lange de diff\u00e9rents constituants<\/strong>. Malgr\u00e9 tout, tu peux sentir l\u2019air lorsqu\u2019il se d\u00e9place sous l\u2019effet du vent, car il constitue l&rsquo;atmosph\u00e8re terrestre.<\/p>\n\n        <\/div>\n              <\/section>\n\n\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter size-full\"><img decoding=\"async\" width=\"500\" height=\"375\" src=\"https:\/\/sherpas.com\/content\/uploads\/2023\/11\/composition-de-lair-1.gif\" alt=\"Le parapluie d'un homme s'envole sous l'effet du vent.\" class=\"wp-image-267923\" \/><\/figure>\n<\/div>\n\n\n<p>\u200b\ud83d\udccd<strong> Rappel : <\/strong>un \u00ab corps pur \u00bb est une mati\u00e8re qui ne comporte qu&rsquo;une esp\u00e8ce chimique.<\/p>\n\n\n\n<p><strong>L\u2019air que tu respires est notamment pr\u00e9sent dans la troposph\u00e8re, <\/strong>la premi\u00e8re et la plus basse couche de l&rsquo;atmosph\u00e8re de la Terre. Quand l\u2019air entre en contact direct avec cette couche, il joue un r\u00f4le essentiel dans la photosynth\u00e8se ou l&rsquo;\u00e9vaporation des oc\u00e9ans.<\/p>\n\n\n<section class=\"you-know\">\n                <div class=\"you-know__title\"><p>\u200b\ud83d\udca1 Le savais-tu ?<\/p>\n<\/div>\n                        <div class=\"you-know__text\">\n            <p><a href=\"https:\/\/sherpas.com\/blog\/lavoisier-chimie\/\">Antoine Lavoisier<\/a>, le p\u00e8re de la chimie moderne, a \u00e9t\u00e9<strong> le premier \u00e0 montrer que l\u2019air poss\u00e8de plusieurs composants<\/strong>, dont du diazote et du dioxyg\u00e8ne. OK, on t\u2019a un peu spoil\u00e9 l\u00e0, mais ne t\u2019en fais pas. On va rentrer dans les d\u00e9tails dans notre deuxi\u00e8me partie !<\/p>\n\n        <\/div>\n              <\/section>\n\n\n<section class=\"read-also\">\n    <p class=\"read-also__title\">\u00c0 lire aussi<\/p>\n            <div class=\"read-also__list\">\n            <p>\ud83e\uddea <a href=\"https:\/\/sherpas.com\/blog\/la-biographie-de-marie-curie\/\">Marie Curie<\/a> : une femme de science !<\/p>\n\n        <\/div>\n    <\/section>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"limportance-et-le-role-de-lair\">L\u2019importance et le r\u00f4le de l\u2019air \u2728<\/h3>\n\n\n\n<p>\u00ab En gros, l\u2019air est indispensable aux \u00eatres humains\u202f? \u00bb. Oui, mais pas que\u202f! Il est vrai que ta vie d\u00e9pend de l&rsquo;oxyg\u00e8ne pr\u00e9sent dans l&rsquo;air, <strong>mais le r\u00f4le de ce fluide gazeux est multiple<\/strong>. Rappelle-toi, on t\u2019a par exemple parl\u00e9 de la photosynth\u00e8se !\u200b\u200b \ud83d\ude0c<\/p>\n\n\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter size-full is-resized\"><img decoding=\"async\" width=\"500\" height=\"205\" src=\"https:\/\/sherpas.com\/content\/uploads\/2023\/11\/composition-de-lair-6.gif\" alt=\"Ron Weasley grimace \u00e0 c\u00f4t\u00e9 d'une plante Mandragore.\" class=\"wp-image-267928\" style=\"width:648px;height:auto\" \/><\/figure>\n<\/div>\n\n\n<p>\u200b\ud83d\udc49<strong> <\/strong>\u200b<strong>Les plantes utilisent le dioxyde de carbone de l&rsquo;air <\/strong>et la lumi\u00e8re du soleil pour effectuer ce processus bio\u00e9nerg\u00e9tique. Il leur permet de produire leur propre nourriture et de lib\u00e9rer de l&rsquo;oxyg\u00e8ne dans l&rsquo;atmosph\u00e8re.<\/p>\n\n\n<section class=\"you-know\">\n                <div class=\"you-know__title\"><p>\u21aa\ufe0f Autres exemples<\/p>\n<\/div>\n                        <div class=\"you-know__text\">\n            <ul>\n<li>La r\u00e9gulation du climat ;<\/li>\n<li>le transport a\u00e9rien ;<\/li>\n<li>l\u2019\u00e9quilibre \u00e9cologique ;<\/li>\n<li>le transfert de chaleur ;<\/li>\n<li>la protection contre les rayons solaires.<\/li>\n<\/ul>\n\n        <\/div>\n              <\/section>\n\n\n\n<p>\u200bLorsqu\u2019on parle de \u00ab transport a\u00e9rien \u00bb, \u00e7a signifie que<strong> l\u2019air permet le transport de pollens, de spores ou de graines<\/strong>, facilitant ainsi la reproduction des plantes.<\/p>\n\n\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter size-full is-resized\"><img decoding=\"async\" width=\"667\" height=\"460\" src=\"https:\/\/sherpas.com\/content\/uploads\/2023\/11\/composition-de-lair-3.jpg\" alt=\"Un homme livre une pizza \u00e0 une femme.\" class=\"wp-image-267927\" style=\"width:593px;height:auto\" srcset=\"https:\/\/xapbm7c37i.cloudimg.io\/https:\/\/sherpas.com\/content\/uploads\/2023\/11\/composition-de-lair-3.jpg?q=85&amp;force_format=webp&amp;org_if_sml=1&amp;w=667 667w, https:\/\/xapbm7c37i.cloudimg.io\/https:\/\/sherpas.com\/content\/uploads\/2023\/11\/composition-de-lair-3.jpg?q=85&amp;force_format=webp&amp;org_if_sml=1&amp;w=300 300w, https:\/\/xapbm7c37i.cloudimg.io\/https:\/\/sherpas.com\/content\/uploads\/2023\/11\/composition-de-lair-3.jpg?q=85&amp;force_format=webp&amp;org_if_sml=1&amp;w=181 181w, https:\/\/xapbm7c37i.cloudimg.io\/https:\/\/sherpas.com\/content\/uploads\/2023\/11\/composition-de-lair-3.jpg?q=85&amp;force_format=webp&amp;org_if_sml=1&amp;w=394 394w, https:\/\/xapbm7c37i.cloudimg.io\/https:\/\/sherpas.com\/content\/uploads\/2023\/11\/composition-de-lair-3.jpg?q=85&amp;force_format=webp&amp;org_if_sml=1&amp;w=288 288w, https:\/\/xapbm7c37i.cloudimg.io\/https:\/\/sherpas.com\/content\/uploads\/2023\/11\/composition-de-lair-3.jpg?q=85&amp;force_format=webp&amp;org_if_sml=1&amp;w=538 538w, https:\/\/xapbm7c37i.cloudimg.io\/https:\/\/sherpas.com\/content\/uploads\/2023\/11\/composition-de-lair-3.jpg?q=85&amp;force_format=webp&amp;org_if_sml=1&amp;w=265 265w, https:\/\/xapbm7c37i.cloudimg.io\/https:\/\/sherpas.com\/content\/uploads\/2023\/11\/composition-de-lair-3.jpg?q=85&amp;force_format=webp&amp;org_if_sml=1&amp;w=60 60w\" sizes=\"(max-width: 667px) 100vw, 667px\" \/><figcaption class=\"wp-element-caption\"><em>Quand l&rsquo;air sert de livreur.<\/em><\/figcaption><\/figure>\n<\/div>\n\n\n<p>\u200b\ud83d\udc49<strong> <\/strong>De m\u00eame, <strong>ce fluide gazeux est un excellent isolant thermique<\/strong>. Il contribue au transfert de la chaleur, que ce soit en retenant la chaleur pr\u00e8s de la surface terrestre (le fameux effet de serre) ou en permettant son refroidissement.<\/p>\n\n\n<section class=\"push \">\n        <div >\n            \n                                                <div class=\"push__container  qcd\" data-target=\"_self\" data-qcd=\"aHR0cHM6Ly9zaGVycGFzLmNvbS9mdW5uZWwtc3R1ZGVudC1xdWFsaWZpY2F0aW9u\" data-banner=\"2\" data-name=\"Cours part\u2019 global #1 = CPG1\" style=\"background-color: #F3FBF7\" >\n                                                                        <div class=\"push__teachers\">\n    <div class=\"d-flex justify-content-center d-md-none\">\n        <img decoding=\"async\" class=\"push__logo\" src=\"\/content\/themes\/sherpas-theme\/dist\/images\/logo.svg\" alt=\"Logo Sherpas\">\n    <\/div>\n    <div class=\"swiper\">\n        <div class=\"swiper-wrapper\">\n                                            <div class=\"swiper-slide\">\n         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          xlink:href=\"\/content\/themes\/sherpas-theme\/dist\/images\/sprite.svg#star\"\/>\n                                    <\/svg>\n                                                            <\/div>\n                                                 <p class=\"push__teachers-price\">12\u20ac\/h<\/p>                     <\/div>\n                <\/div>\n                                            <div class=\"swiper-slide\">\n                    <div class=\"push__teachers-card\">\n                        <div\n                            class=\"push__teachers-profil\"\n                            \n                            style=\"background-image: url(https:\/\/sherpas.com\/content\/uploads\/2022\/01\/Thibault2x.png);\"\n                        >\n                    <\/div>\n                         <p class=\"push__teachers-name\">Thibault<\/p>                          <p class=\"push__teachers-school\">ENS Paris Ulm<\/p>                                                     <div class=\"push__teachers-note\">\n                                                                    <svg  class=\"active\" >\n                                        <use\n                                            xlink:href=\"\/content\/themes\/sherpas-theme\/dist\/images\/sprite.svg#star\"\/>\n                                    <\/svg>\n                                                                    <svg  class=\"active\" >\n                                        <use\n                                            xlink:href=\"\/content\/themes\/sherpas-theme\/dist\/images\/sprite.svg#star\"\/>\n                                    <\/svg>\n                                                                    <svg  class=\"active\" >\n                                        <use\n                                            xlink:href=\"\/content\/themes\/sherpas-theme\/dist\/images\/sprite.svg#star\"\/>\n                                    <\/svg>\n                            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       class=\"push__teachers-profil\"\n                            \n                            style=\"background-image: url(https:\/\/sherpas.com\/content\/uploads\/2022\/01\/Victor2x.jpg);\"\n                        >\n                    <\/div>\n                         <p class=\"push__teachers-name\">Victor<\/p>                          <p class=\"push__teachers-school\">ESCP<\/p>                                                     <div class=\"push__teachers-note\">\n                                                                    <svg  class=\"active\" >\n                                        <use\n                                            xlink:href=\"\/content\/themes\/sherpas-theme\/dist\/images\/sprite.svg#star\"\/>\n                                    <\/svg>\n                                                                    <svg  class=\"active\" >\n                                        <use\n                                            xlink:href=\"\/content\/themes\/sherpas-theme\/dist\/images\/sprite.svg#star\"\/>\n                                    <\/svg>\n                                                                    <svg  class=\"active\" >\n                                        <use\n                                            xlink:href=\"\/content\/themes\/sherpas-theme\/dist\/images\/sprite.svg#star\"\/>\n                                    <\/svg>\n                                                                    <svg  class=\"active\" >\n                                        <use\n                                            xlink:href=\"\/content\/themes\/sherpas-theme\/dist\/images\/sprite.svg#star\"\/>\n                                    <\/svg>\n                                                                    <svg  class=\"active\" >\n                                        <use\n                                            xlink:href=\"\/content\/themes\/sherpas-theme\/dist\/images\/sprite.svg#star\"\/>\n                                    <\/svg>\n                                                            <\/div>\n                                                 <p class=\"push__teachers-price\">25\u20ac\/h<\/p>                     <\/div>\n                <\/div>\n                                            <div class=\"swiper-slide\">\n                    <div class=\"push__teachers-card\">\n                        <div\n                            class=\"push__teachers-profil\"\n                            \n                            style=\"background-image: url(https:\/\/sherpas.com\/content\/uploads\/2022\/01\/Agathe2x.png);\"\n                        >\n                    <\/div>\n                         <p class=\"push__teachers-name\">Agathe<\/p>                          <p class=\"push__teachers-school\">ENS Lyon<\/p>                                                     <div class=\"push__teachers-note\">\n                                                                    <svg  class=\"active\" >\n                                        <use\n                                            xlink:href=\"\/content\/themes\/sherpas-theme\/dist\/images\/sprite.svg#star\"\/>\n                                    <\/svg>\n                                                                    <svg  class=\"active\" >\n                                        <use\n                                            xlink:href=\"\/content\/themes\/sherpas-theme\/dist\/images\/sprite.svg#star\"\/>\n                                    <\/svg>\n                                                                    <svg  class=\"active\" >\n                                        <use\n                                            xlink:href=\"\/content\/themes\/sherpas-theme\/dist\/images\/sprite.svg#star\"\/>\n                                    <\/svg>\n                                                                    <svg  class=\"active\" >\n                                        <use\n                                            xlink:href=\"\/content\/themes\/sherpas-theme\/dist\/images\/sprite.svg#star\"\/>\n                                    <\/svg>\n                                                                    <svg  class=\"active\" >\n                                        <use\n                                            xlink:href=\"\/content\/themes\/sherpas-theme\/dist\/images\/sprite.svg#star\"\/>\n                                    <\/svg>\n                                                            <\/div>\n                                                 <p class=\"push__teachers-price\">19\u20ac\/h<\/p>                     <\/div>\n                <\/div>\n                                            <div class=\"swiper-slide\">\n                    <div class=\"push__teachers-card\">\n                        <div\n                            class=\"push__teachers-profil\"\n                            \n                            style=\"background-image: url(https:\/\/sherpas.com\/content\/uploads\/2022\/01\/Louise2x.png);\"\n                        >\n                    <\/div>\n                         <p class=\"push__teachers-name\">Louise<\/p>                          <p class=\"push__teachers-school\">Mines ParisTech<\/p>                                                     <div class=\"push__teachers-note\">\n                                                                    <svg  class=\"active\" >\n                                        <use\n                                            xlink:href=\"\/content\/themes\/sherpas-theme\/dist\/images\/sprite.svg#star\"\/>\n                                    <\/svg>\n                                                                    <svg  class=\"active\" >\n                                        <use\n                                            xlink:href=\"\/content\/themes\/sherpas-theme\/dist\/images\/sprite.svg#star\"\/>\n                                    <\/svg>\n                                                                    <svg  class=\"active\" >\n                                        <use\n                                            xlink:href=\"\/content\/themes\/sherpas-theme\/dist\/images\/sprite.svg#star\"\/>\n                                    <\/svg>\n                                                                    <svg  class=\"active\" >\n                                        <use\n                                            xlink:href=\"\/content\/themes\/sherpas-theme\/dist\/images\/sprite.svg#star\"\/>\n                                    <\/svg>\n                                                                    <svg  class=\"active\" >\n                                        <use\n                                            xlink:href=\"\/content\/themes\/sherpas-theme\/dist\/images\/sprite.svg#star\"\/>\n                                    <\/svg>\n                                                            <\/div>\n                                                 <p class=\"push__teachers-price\">24\u20ac\/h<\/p>                     <\/div>\n                <\/div>\n                                            <div class=\"swiper-slide\">\n                    <div class=\"push__teachers-card\">\n                        <div\n                            class=\"push__teachers-profil\"\n                            \n                            style=\"background-image: url(https:\/\/sherpas.com\/content\/uploads\/2022\/01\/Fanny2x.jpg);\"\n                        >\n                    <\/div>\n                         <p class=\"push__teachers-name\">Fanny<\/p>                          <p class=\"push__teachers-school\">Ponts ParisTech<\/p>                                                     <div class=\"push__teachers-note\">\n                                                                    <svg  class=\"active\" >\n                                        <use\n                                            xlink:href=\"\/content\/themes\/sherpas-theme\/dist\/images\/sprite.svg#star\"\/>\n                                    <\/svg>\n                                                                    <svg  class=\"active\" >\n                                        <use\n                                            xlink:href=\"\/content\/themes\/sherpas-theme\/dist\/images\/sprite.svg#star\"\/>\n                                    <\/svg>\n                                                                    <svg  class=\"active\" >\n                                        <use\n                                            xlink:href=\"\/content\/themes\/sherpas-theme\/dist\/images\/sprite.svg#star\"\/>\n                                    <\/svg>\n                                                                    <svg  class=\"active\" >\n                                        <use\n                                            xlink:href=\"\/content\/themes\/sherpas-theme\/dist\/images\/sprite.svg#star\"\/>\n                                    <\/svg>\n                                                                    <svg  class=\"active\" >\n                                        <use\n                                            xlink:href=\"\/content\/themes\/sherpas-theme\/dist\/images\/sprite.svg#star\"\/>\n                                    <\/svg>\n                                                            <\/div>\n                                                 <p class=\"push__teachers-price\">19\u20ac\/h<\/p>                     <\/div>\n                <\/div>\n                                            <div class=\"swiper-slide\">\n                    <div class=\"push__teachers-card\">\n                        <div\n                            class=\"push__teachers-profil\"\n                            \n                            style=\"background-image: url(https:\/\/sherpas.com\/content\/uploads\/2022\/01\/Noemie2x.jpg);\"\n                        >\n                    <\/div>\n                         <p class=\"push__teachers-name\">No\u00e9mie<\/p>                          <p class=\"push__teachers-school\">M2 en droit \u00e0 Assas<\/p>                                                     <div class=\"push__teachers-note\">\n                                                                    <svg  class=\"active\" >\n                                        <use\n                                            xlink:href=\"\/content\/themes\/sherpas-theme\/dist\/images\/sprite.svg#star\"\/>\n                                    <\/svg>\n                                                                    <svg  class=\"active\" >\n                                        <use\n                                            xlink:href=\"\/content\/themes\/sherpas-theme\/dist\/images\/sprite.svg#star\"\/>\n                                    <\/svg>\n                                                                    <svg  class=\"active\" >\n                                        <use\n                                            xlink:href=\"\/content\/themes\/sherpas-theme\/dist\/images\/sprite.svg#star\"\/>\n                                    <\/svg>\n                                                                    <svg  class=\"active\" >\n                                        <use\n                                            xlink:href=\"\/content\/themes\/sherpas-theme\/dist\/images\/sprite.svg#star\"\/>\n                                    <\/svg>\n                                                                    <svg  class=\"active\" >\n                                        <use\n                                            xlink:href=\"\/content\/themes\/sherpas-theme\/dist\/images\/sprite.svg#star\"\/>\n                                    <\/svg>\n                                                            <\/div>\n                                                 <p class=\"push__teachers-price\">19\u20ac\/h<\/p>                     <\/div>\n                <\/div>\n                                            <div class=\"swiper-slide\">\n                    <div class=\"push__teachers-card\">\n                        <div\n                            class=\"push__teachers-profil\"\n                            \n                            style=\"background-image: url(https:\/\/sherpas.com\/content\/uploads\/2022\/01\/David2x.jpg);\"\n                        >\n                    <\/div>\n                         <p class=\"push__teachers-name\">David<\/p>                          <p class=\"push__teachers-school\">EDHEC<\/p>                                                     <div class=\"push__teachers-note\">\n                                                                    <svg  class=\"active\" >\n                                        <use\n                                            xlink:href=\"\/content\/themes\/sherpas-theme\/dist\/images\/sprite.svg#star\"\/>\n                                    <\/svg>\n                                                                    <svg  class=\"active\" >\n                                        <use\n                                            xlink:href=\"\/content\/themes\/sherpas-theme\/dist\/images\/sprite.svg#star\"\/>\n                                    <\/svg>\n                                                                    <svg  class=\"active\" >\n                                        <use\n                                            xlink:href=\"\/content\/themes\/sherpas-theme\/dist\/images\/sprite.svg#star\"\/>\n                                    <\/svg>\n                                                                    <svg  class=\"active\" >\n                                        <use\n                                            xlink:href=\"\/content\/themes\/sherpas-theme\/dist\/images\/sprite.svg#star\"\/>\n                                    <\/svg>\n                                                                    <svg  class=\"active\" >\n                                        <use\n                                            xlink:href=\"\/content\/themes\/sherpas-theme\/dist\/images\/sprite.svg#star\"\/>\n                                    <\/svg>\n                                                            <\/div>\n                                                 <p class=\"push__teachers-price\">25\u20ac\/h<\/p>                     <\/div>\n                <\/div>\n                    <\/div>\n    <\/div>\n<\/div>\n                                                    <div class=\"push__content\">\n                                                            <div  class=\"d-none d-md-block\" >\n                                    <img decoding=\"async\" class=\"push__logo\" src=\"\/content\/themes\/sherpas-theme\/dist\/images\/logo.svg\"\n                                        alt=\"Logo Sherpas\">\n                                <\/div>\n                                                                                        <div class=\"push__title\"><p>Ton premier cours particulier est offert ! <span role=\"img\" aria-label=\"\ud83c\udf81\">\ud83c\udf81<\/span><!-- notionvc: 91b6b7d7-50f2-46f4-ae1f-ecbabe834aad --><\/p>\n<\/div>\n                                                                                        <div class=\"push__text\"><p>Nos profs sont pass\u00e9s par les meilleures \u00e9coles et universit\u00e9s.<!-- notionvc: 21bb66b6-b36d-4ce8-8950-173722d75a1e --><\/p>\n<p>&nbsp;<\/p>\n<\/div>\n                                                        <div class=\"push__promo-button   \">\n                                                                                                    <div\n                                        class=\"btn btn-primary\"\n                                        style=\"color: #ffffff; border-color: ; background-color: \"\n\n                                    >\n                                        J&rsquo;EN PROFITE MAINTENANT !\n                                    <\/div>\n                                                            <\/div>\n                                                    <\/div>\n                                    <\/div>\n                                    <\/div>\n    <\/section>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"de-quoi-est-compose-lair\">De quoi est compos\u00e9 l\u2019air ?\u200b \u2601\ufe0f<\/h2>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"un-melange-de-gaz-inegal\">Un m\u00e9lange de gaz in\u00e9gal \u2696\ufe0f<\/h3>\n\n\n\n<p>Maintenant que tu es incollable sur la d\u00e9finition et le r\u00f4le de cette mati\u00e8re, passons \u00e0 la composition de l\u2019air. Comme on te l\u2019a expliqu\u00e9, <strong>c\u2019est un m\u00e9lange de corps purs \u00e0 l\u2019\u00e9tat gazeux<\/strong>. En volume, l\u2019air se compose de :<\/p>\n\n\n<section class=\"you-know\">\n                <div class=\"you-know__title\"><\/div>\n                        <div class=\"you-know__text\">\n            <ul>\n<li>78 % de diazote (N\u2082) ;<\/li>\n<li>21 % de dioxyg\u00e8ne (O\u2082) ;<\/li>\n<li>1 % d&rsquo;autres gaz divers.<\/li>\n<\/ul>\n\n        <\/div>\n              <\/section>\n\n\n\n<p>\u200b\ud83d\udc49<strong> <\/strong>Dans ce 1%, tu as par exemple de l\u2019argon (Ar), du dioxyde de carbone (CO<sub>2<\/sub>), de l\u2019hydrog\u00e8ne (H2), de la vapeur d&rsquo;eau et de l\u2019ozone (O\u2083). En g\u00e9n\u00e9ral, <strong>on retient que l\u2019air est constitu\u00e9 d\u2019environ 20 % de dioxyg\u00e8ne et de 80 % de diazote<\/strong>. C\u2019est simple \u00e0 retenir !\u200b \ud83e\udd2d<\/p>\n\n\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter size-full\"><img decoding=\"async\" width=\"402\" height=\"450\" src=\"https:\/\/sherpas.com\/content\/uploads\/2023\/11\/composition-de-lair-schema.png\" alt=\"Un camembert illustre la r\u00e9partition des gaz dans la composition de l'air.\" class=\"wp-image-267930\" srcset=\"https:\/\/xapbm7c37i.cloudimg.io\/https:\/\/sherpas.com\/content\/uploads\/2023\/11\/composition-de-lair-schema.png?q=85&amp;force_format=webp&amp;org_if_sml=1&amp;w=402 402w, https:\/\/xapbm7c37i.cloudimg.io\/https:\/\/sherpas.com\/content\/uploads\/2023\/11\/composition-de-lair-schema.png?q=85&amp;force_format=webp&amp;org_if_sml=1&amp;w=268 268w, https:\/\/xapbm7c37i.cloudimg.io\/https:\/\/sherpas.com\/content\/uploads\/2023\/11\/composition-de-lair-schema.png?q=85&amp;force_format=webp&amp;org_if_sml=1&amp;w=112 112w, https:\/\/xapbm7c37i.cloudimg.io\/https:\/\/sherpas.com\/content\/uploads\/2023\/11\/composition-de-lair-schema.png?q=85&amp;force_format=webp&amp;org_if_sml=1&amp;w=243 243w, https:\/\/xapbm7c37i.cloudimg.io\/https:\/\/sherpas.com\/content\/uploads\/2023\/11\/composition-de-lair-schema.png?q=85&amp;force_format=webp&amp;org_if_sml=1&amp;w=288 288w, https:\/\/xapbm7c37i.cloudimg.io\/https:\/\/sherpas.com\/content\/uploads\/2023\/11\/composition-de-lair-schema.png?q=85&amp;force_format=webp&amp;org_if_sml=1&amp;w=331 331w, https:\/\/xapbm7c37i.cloudimg.io\/https:\/\/sherpas.com\/content\/uploads\/2023\/11\/composition-de-lair-schema.png?q=85&amp;force_format=webp&amp;org_if_sml=1&amp;w=265 265w, https:\/\/xapbm7c37i.cloudimg.io\/https:\/\/sherpas.com\/content\/uploads\/2023\/11\/composition-de-lair-schema.png?q=85&amp;force_format=webp&amp;org_if_sml=1&amp;w=54 54w\" sizes=\"(max-width: 402px) 100vw, 402px\" \/><\/figure>\n<\/div>\n\n\n<p>On peut aussi trouver <strong>des traces de n\u00e9on, de krypton, de x\u00e9non, d&rsquo;h\u00e9lium<\/strong>\u2026 Oui oui, on sait, on dirait une liste de composants servant \u00e0 former la kryptonite de Superman.\u200b \ud83d\udc8e<\/p>\n\n\n\n<p>\u200b\ud83d\udccd<strong> Note : <\/strong>la concentration de vapeur d\u2019eau peut varier dans le temps et l&rsquo;espace. Par exemple, le volume de vapeur d&rsquo;eau d\u2019un air froid ne d\u00e9passera pas les 0,6 % alors qu\u2019il pourra monter jusqu&rsquo;\u00e0 plus de 4 % dans un air chaud. Incroyable, non ?\u200b \ud83d\ude0e<\/p>\n\n\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter size-full is-resized\"><img decoding=\"async\" width=\"480\" height=\"342\" src=\"https:\/\/sherpas.com\/content\/uploads\/2023\/11\/composition-de-lair-superman.gif\" alt=\"Superman vole et d\u00e9truit des m\u00e9t\u00e9ores.\" class=\"wp-image-267931\" style=\"width:490px;height:auto\" \/><\/figure>\n<\/div>\n\n\n<p>Tu es perdu avec les formules des atomes et des mol\u00e9cules\u202f? Tu as besoin d\u2019un coup de pouce pour r\u00e9viser le tableau p\u00e9riodique des \u00e9l\u00e9ments, alias le <a href=\"https:\/\/sherpas.com\/blog\/tableau-de-mendeleiev\/\">tableau de Mendele\u00efev<\/a> ? Prends des <a href=\"https:\/\/sherpas.com\/cours\/physique\">cours particuliers de physique<\/a> avec un Sherpa !<\/p>\n\n\n<section class=\"read-also\">\n    <p class=\"read-also__title\">\u00c0 lire aussi<\/p>\n            <div class=\"read-also__list\">\n            <p>\ud83d\udca1 <a href=\"https:\/\/sherpas.com\/blog\/vitesse-lumiere\/\">Vitesse de la lumi\u00e8re<\/a> : qu\u00e9saco ?<\/p>\n\n        <\/div>\n    <\/section>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"la-pollution-de-lair\">La pollution de l\u2019air\u200b \ud83d\ude36\u200d\ud83c\udf2b\ufe0f<\/h3>\n\n\n\n<p>As-tu d\u00e9j\u00e0 entendu que l\u2019air de la campagne \u00e9tait plus pur que l\u2019air de la ville\u202f? Si on pense souvent que les lieux moins fr\u00e9quent\u00e9s sont mieux pour notre sant\u00e9, c\u2019est parce que<strong> la pollution atmosph\u00e9rique est susceptible de modifier la composition de l\u2019air<\/strong>.\u200b \ud83d\ude2c<\/p>\n\n\n<section class=\"you-know\">\n                <div class=\"you-know__title\"><p>\u200b\ud83d\udd0e D\u00e9finition<\/p>\n<\/div>\n                        <div class=\"you-know__text\">\n            <p>En physique-chimie, la \u00ab pollution de l\u2019air \u00bb d\u00e9signe<strong> l\u2019ensemble des gaz et des particules qui sont pr\u00e9sents en suspension dans l&rsquo;air<\/strong>. Comme tu t\u2019en doutes, ils sont nuisibles pour les \u00eatres vivants, l&rsquo;environnement, le climat, etc.\u200b \ud83d\ude16<\/p>\n\n        <\/div>\n              <\/section>\n\n\n\n<p>\u200b\ud83d\udc49<strong> <\/strong>Pourquoi alt\u00e9ration de la qualit\u00e9 de l&rsquo;air\u202f? <strong>Plusieurs causes entrent en jeu<\/strong>, car l&rsquo;air v\u00e9hicule de nombreux \u00e9l\u00e9ments comme :<\/p>\n\n\n<section class=\"you-know\">\n                <div class=\"you-know__title\"><\/div>\n                        <div class=\"you-know__text\">\n            <ul>\n<li>des particules de pollen ;<\/li>\n<li>des a\u00e9rosols ;<\/li>\n<li>des corps d\u2019\u00e9ruptions volcaniques ;<\/li>\n<li>des polluants industriels.<\/li>\n<\/ul>\n\n        <\/div>\n              <\/section>\n\n\n\n<p>\u00c9videmment, <strong>m\u00eame les zones rurales peuvent \u00eatre affect\u00e9es<\/strong> par des facteurs tels que les \u00e9missions agricoles ou les feux de biomasse (\u200bles incendies dans les espaces naturels\u200b \ud83d\udd25). La lutte contre la pollution de l&rsquo;air est donc cruciale pour pr\u00e9server l&rsquo;environnement.<\/p>\n\n\n<section class=\"push \">\n        <div >\n            \n                                                <div class=\"push__container  qcd\" data-target=\"_self\" data-qcd=\"aHR0cHM6Ly9zaGVycGFzLmNvbS9mdW5uZWwtc3R1ZGVudC1xdWFsaWZpY2F0aW9u\" data-banner=\"2\" data-name=\"Cours part\u2019 global #2 = CPG2\" style=\"background-color: #F3FBF7\" >\n                                                                        <div class=\"push__teachers\">\n    <div class=\"d-flex justify-content-center d-md-none\">\n        <img decoding=\"async\" class=\"push__logo\" src=\"\/content\/themes\/sherpas-theme\/dist\/images\/logo.svg\" alt=\"Logo Sherpas\">\n    <\/div>\n    <div class=\"swiper\">\n        <div class=\"swiper-wrapper\">\n                                            <div class=\"swiper-slide\">\n                    <div class=\"push__teachers-card\">\n                        <div\n                            class=\"push__teachers-profil\"\n                            \n                            style=\"background-image: url(https:\/\/sherpas.com\/content\/uploads\/2022\/01\/Cle\u0301mence2x.png);\"\n                        >\n                    <\/div>\n                         <p class=\"push__teachers-name\">Cl\u00e9mence<\/p>                          <p class=\"push__teachers-school\">HEC Paris<\/p>                                                     <div class=\"push__teachers-note\">\n                                                                    <svg  class=\"active\" >\n                                        <use\n                                            xlink:href=\"\/content\/themes\/sherpas-theme\/dist\/images\/sprite.svg#star\"\/>\n                                    <\/svg>\n                                                                    <svg  class=\"active\" >\n                                        <use\n                                            xlink:href=\"\/content\/themes\/sherpas-theme\/dist\/images\/sprite.svg#star\"\/>\n                                    <\/svg>\n                                                                    <svg  class=\"active\" >\n                                        <use\n                                            xlink:href=\"\/content\/themes\/sherpas-theme\/dist\/images\/sprite.svg#star\"\/>\n                                    <\/svg>\n                                                                    <svg  class=\"active\" >\n                                        <use\n                                            xlink:href=\"\/content\/themes\/sherpas-theme\/dist\/images\/sprite.svg#star\"\/>\n                                    <\/svg>\n                                                                    <svg  class=\"active\" >\n                                        <use\n                                            xlink:href=\"\/content\/themes\/sherpas-theme\/dist\/images\/sprite.svg#star\"\/>\n                                    <\/svg>\n                                                            <\/div>\n                                                 <p class=\"push__teachers-price\">21\u20ac\/h\/h<\/p>                     <\/div>\n                <\/div>\n                                            <div class=\"swiper-slide\">\n                    <div class=\"push__teachers-card\">\n                        <div\n                            class=\"push__teachers-profil\"\n                            \n                            style=\"background-image: url(https:\/\/sherpas.com\/content\/uploads\/2022\/01\/Thibault2x.png);\"\n                        >\n                    <\/div>\n                         <p class=\"push__teachers-name\">Thibault<\/p>                          <p class=\"push__teachers-school\">ENS Paris Ulm<\/p>                                                     <div class=\"push__teachers-note\">\n                                                                    <svg  class=\"active\" >\n                                        <use\n                                            xlink:href=\"\/content\/themes\/sherpas-theme\/dist\/images\/sprite.svg#star\"\/>\n                                    <\/svg>\n                                                                    <svg  class=\"active\" >\n                                        <use\n                                            xlink:href=\"\/content\/themes\/sherpas-theme\/dist\/images\/sprite.svg#star\"\/>\n                                    <\/svg>\n                                                                    <svg  class=\"active\" >\n                                        <use\n                                            xlink:href=\"\/content\/themes\/sherpas-theme\/dist\/images\/sprite.svg#star\"\/>\n                                    <\/svg>\n                                                                    <svg  class=\"active\" >\n                                        <use\n                                            xlink:href=\"\/content\/themes\/sherpas-theme\/dist\/images\/sprite.svg#star\"\/>\n                                    <\/svg>\n                                                                    <svg  class=\"active\" >\n                                        <use\n                                            xlink:href=\"\/content\/themes\/sherpas-theme\/dist\/images\/sprite.svg#star\"\/>\n                                    <\/svg>\n                                                            <\/div>\n                                                 <p class=\"push__teachers-price\">20\u20ac\/h<\/p>                     <\/div>\n                <\/div>\n                                            <div class=\"swiper-slide\">\n                    <div class=\"push__teachers-card\">\n                        <div\n                            class=\"push__teachers-profil\"\n                            \n                            style=\"background-image: url(https:\/\/sherpas.com\/content\/uploads\/2022\/01\/Sophie2x.png);\"\n                        >\n                    <\/div>\n                         <p class=\"push__teachers-name\">Sophie<\/p>                          <p class=\"push__teachers-school\">Sciences Po Bordeaux<\/p>                                                     <div class=\"push__teachers-note\">\n                                                                    <svg  class=\"active\" >\n                                        <use\n                                            xlink:href=\"\/content\/themes\/sherpas-theme\/dist\/images\/sprite.svg#star\"\/>\n                                    <\/svg>\n                                                                    <svg  class=\"active\" >\n                                        <use\n                                            xlink:href=\"\/content\/themes\/sherpas-theme\/dist\/images\/sprite.svg#star\"\/>\n                                    <\/svg>\n                                                                    <svg  class=\"active\" >\n                                        <use\n                                            xlink:href=\"\/content\/themes\/sherpas-theme\/dist\/images\/sprite.svg#star\"\/>\n                                    <\/svg>\n                                                                    <svg  class=\"active\" >\n                                        <use\n                                            xlink:href=\"\/content\/themes\/sherpas-theme\/dist\/images\/sprite.svg#star\"\/>\n                                    <\/svg>\n                                                                    <svg >\n                                        <use\n                                            xlink:href=\"\/content\/themes\/sherpas-theme\/dist\/images\/sprite.svg#star\"\/>\n                                    <\/svg>\n                                                            <\/div>\n                                                 <p class=\"push__teachers-price\">12\u20ac\/h<\/p>                     <\/div>\n                <\/div>\n                                            <div class=\"swiper-slide\">\n                    <div class=\"push__teachers-card\">\n                        <div\n                            class=\"push__teachers-profil\"\n                            \n                            style=\"background-image: url(https:\/\/sherpas.com\/content\/uploads\/2022\/01\/Noemie2x.jpg);\"\n                        >\n                    <\/div>\n                         <p class=\"push__teachers-name\">No\u00e9mie<\/p>                          <p class=\"push__teachers-school\">M2 en droit \u00e0 Assas<\/p>                                                     <div class=\"push__teachers-note\">\n                                                                    <svg  class=\"active\" >\n                                        <use\n                                            xlink:href=\"\/content\/themes\/sherpas-theme\/dist\/images\/sprite.svg#star\"\/>\n                                    <\/svg>\n                                                                    <svg  class=\"active\" >\n                                        <use\n                                            xlink:href=\"\/content\/themes\/sherpas-theme\/dist\/images\/sprite.svg#star\"\/>\n                                    <\/svg>\n                                                                    <svg  class=\"active\" >\n                                        <use\n                                            xlink:href=\"\/content\/themes\/sherpas-theme\/dist\/images\/sprite.svg#star\"\/>\n                                    <\/svg>\n                                                                    <svg  class=\"active\" >\n                                        <use\n                                            xlink:href=\"\/content\/themes\/sherpas-theme\/dist\/images\/sprite.svg#star\"\/>\n                                    <\/svg>\n                                                                    <svg  class=\"active\" >\n                                        <use\n                                            xlink:href=\"\/content\/themes\/sherpas-theme\/dist\/images\/sprite.svg#star\"\/>\n                                    <\/svg>\n                                                            <\/div>\n                                                 <p class=\"push__teachers-price\">19\u20ac\/h<\/p>                     <\/div>\n                <\/div>\n                                            <div class=\"swiper-slide\">\n                    <div class=\"push__teachers-card\">\n                        <div\n                            class=\"push__teachers-profil\"\n                            \n                            style=\"background-image: url(https:\/\/sherpas.com\/content\/uploads\/2022\/01\/Fanny2x.jpg);\"\n                        >\n                    <\/div>\n                         <p class=\"push__teachers-name\">Fanny<\/p>                          <p class=\"push__teachers-school\">Ponts ParisTech<\/p>                                                     <div class=\"push__teachers-note\">\n                                                                    <svg  class=\"active\" >\n                                        <use\n                                            xlink:href=\"\/content\/themes\/sherpas-theme\/dist\/images\/sprite.svg#star\"\/>\n                                    <\/svg>\n                                                                    <svg  class=\"active\" >\n                                        <use\n                                            xlink:href=\"\/content\/themes\/sherpas-theme\/dist\/images\/sprite.svg#star\"\/>\n                                    <\/svg>\n                                                                    <svg  class=\"active\" >\n                                        <use\n                                            xlink:href=\"\/content\/themes\/sherpas-theme\/dist\/images\/sprite.svg#star\"\/>\n                                    <\/svg>\n                                                                    <svg  class=\"active\" >\n                                        <use\n                                            xlink:href=\"\/content\/themes\/sherpas-theme\/dist\/images\/sprite.svg#star\"\/>\n                                    <\/svg>\n                                                                    <svg  class=\"active\" >\n                                        <use\n                                            xlink:href=\"\/content\/themes\/sherpas-theme\/dist\/images\/sprite.svg#star\"\/>\n                                    <\/svg>\n                                                            <\/div>\n                                                 <p class=\"push__teachers-price\">19\u20ac\/h<\/p>                     <\/div>\n                <\/div>\n                                            <div class=\"swiper-slide\">\n                    <div class=\"push__teachers-card\">\n                        <div\n                            class=\"push__teachers-profil\"\n                            \n                            style=\"background-image: url(https:\/\/sherpas.com\/content\/uploads\/2022\/01\/Simon2x.jpg);\"\n                        >\n                    <\/div>\n                         <p class=\"push__teachers-name\">Simon<\/p>                          <p class=\"push__teachers-school\">4e ann\u00e9e de m\u00e9decine<\/p>                                                     <div class=\"push__teachers-note\">\n                                                                    <svg  class=\"active\" >\n                                        <use\n                                            xlink:href=\"\/content\/themes\/sherpas-theme\/dist\/images\/sprite.svg#star\"\/>\n                                    <\/svg>\n                                                                    <svg  class=\"active\" >\n                                        <use\n                                            xlink:href=\"\/content\/themes\/sherpas-theme\/dist\/images\/sprite.svg#star\"\/>\n                                    <\/svg>\n                                                                    <svg  class=\"active\" >\n                                        <use\n                                            xlink:href=\"\/content\/themes\/sherpas-theme\/dist\/images\/sprite.svg#star\"\/>\n                                    <\/svg>\n                                                                    <svg  class=\"active\" >\n                                        <use\n                                            xlink:href=\"\/content\/themes\/sherpas-theme\/dist\/images\/sprite.svg#star\"\/>\n                                    <\/svg>\n                                                                    <svg  class=\"active\" >\n                                        <use\n                                            xlink:href=\"\/content\/themes\/sherpas-theme\/dist\/images\/sprite.svg#star\"\/>\n                                    <\/svg>\n                                                            <\/div>\n                                                 <p class=\"push__teachers-price\">26\u20ac\/h<\/p>                     <\/div>\n                <\/div>\n                                            <div class=\"swiper-slide\">\n                    <div class=\"push__teachers-card\">\n                        <div\n                            class=\"push__teachers-profil\"\n                            \n                            style=\"background-image: url(https:\/\/sherpas.com\/content\/uploads\/2022\/01\/Nicolas2x.png);\"\n                        >\n                    <\/div>\n                         <p class=\"push__teachers-name\">Nicolas<\/p>                          <p class=\"push__teachers-school\">CentraleSup\u00e9lec<\/p>                                                     <div class=\"push__teachers-note\">\n                                                                    <svg  class=\"active\" >\n                                        <use\n                                            xlink:href=\"\/content\/themes\/sherpas-theme\/dist\/images\/sprite.svg#star\"\/>\n                                    <\/svg>\n                                                                    <svg  class=\"active\" >\n                                        <use\n                                            xlink:href=\"\/content\/themes\/sherpas-theme\/dist\/images\/sprite.svg#star\"\/>\n                                    <\/svg>\n                                                                    <svg  class=\"active\" >\n                                        <use\n                                            xlink:href=\"\/content\/themes\/sherpas-theme\/dist\/images\/sprite.svg#star\"\/>\n                                    <\/svg>\n                                                                    <svg  class=\"active\" >\n                                        <use\n                                            xlink:href=\"\/content\/themes\/sherpas-theme\/dist\/images\/sprite.svg#star\"\/>\n                                    <\/svg>\n                                                                    <svg  class=\"active\" >\n                                        <use\n                                            xlink:href=\"\/content\/themes\/sherpas-theme\/dist\/images\/sprite.svg#star\"\/>\n                                    <\/svg>\n                                                            <\/div>\n                                                 <p class=\"push__teachers-price\">17\u20ac\/h<\/p>                     <\/div>\n                <\/div>\n                                            <div class=\"swiper-slide\">\n                    <div class=\"push__teachers-card\">\n                        <div\n                            class=\"push__teachers-profil\"\n                            \n                            style=\"background-image: url(https:\/\/sherpas.com\/content\/uploads\/2022\/01\/Victor2x.jpg);\"\n                        >\n                    <\/div>\n                         <p class=\"push__teachers-name\">Victor<\/p>                          <p class=\"push__teachers-school\">ESCP<\/p>                                                     <div class=\"push__teachers-note\">\n                                                                    <svg  class=\"active\" >\n                                        <use\n                                            xlink:href=\"\/content\/themes\/sherpas-theme\/dist\/images\/sprite.svg#star\"\/>\n                                    <\/svg>\n                                                                    <svg  class=\"active\" >\n                                        <use\n                                            xlink:href=\"\/content\/themes\/sherpas-theme\/dist\/images\/sprite.svg#star\"\/>\n                                    <\/svg>\n                                                                    <svg  class=\"active\" >\n                                        <use\n                                            xlink:href=\"\/content\/themes\/sherpas-theme\/dist\/images\/sprite.svg#star\"\/>\n                                    <\/svg>\n                                 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       <div  class=\"d-none d-md-block\" >\n                                    <img decoding=\"async\" class=\"push__logo\" src=\"\/content\/themes\/sherpas-theme\/dist\/images\/logo.svg\"\n                                        alt=\"Logo Sherpas\">\n                                <\/div>\n                                                                                        <div class=\"push__title\"><p>Besoin d&rsquo;un prof particulier ? <span role=\"img\" aria-label=\"\u2728\">\u2728<\/span><!-- notionvc: 9b5ed38b-ea2e-4d3c-a3bb-f0091c2eedd2 --><\/p>\n<\/div>\n                                                                                        <div class=\"push__text\"><p>Nos profs sont l\u00e0 pour t&rsquo;aider \u00e0 progresser !<\/p>\n<p>&nbsp;<\/p>\n<p><!-- notionvc: 20490bdd-6579-484b-9d99-0ff0bc1aa8e7 --><\/p>\n<\/div>\n                                                        <div class=\"push__promo-button   \">\n                                                                                                    <div\n                                        class=\"btn btn-primary\"\n                                        style=\"color: ; border-color: ; background-color: \"\n\n                                    >\n                                        JE PRENDS UN COURS OFFERT !\n                                    <\/div>\n                                                            <\/div>\n                                                    <\/div>\n                                    <\/div>\n                                    <\/div>\n    <\/section>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"lair-un-fluide-gazeux-qui-se-mesure\">L\u2019air, un fluide gazeux qui se mesure !\u200b \ud83d\udccf<\/h2>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"la-pression-atmospherique\">La pression atmosph\u00e9rique\u200b \ud83d\udcaa<\/h3>\n\n\n\n<p>Autre notion cl\u00e9 : la pression atmosph\u00e9rique\u202f! C\u2019est<strong> la <\/strong><a href=\"https:\/\/sherpas.com\/blog\/cest-quoi-une-force-en-physique\/\"><strong>force<\/strong><\/a><strong> exerc\u00e9e par l&rsquo;air environnant sur toutes les surfaces expos\u00e9es<\/strong> \u00e0 ce fluide gazeux. En d\u2019autres termes, cette pression est g\u00e9n\u00e9r\u00e9e par le poids des mol\u00e9cules d&rsquo;air qui constituent l&rsquo;atmosph\u00e8re terrestre.<\/p>\n\n\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter size-full is-resized\"><img decoding=\"async\" width=\"500\" height=\"280\" src=\"https:\/\/sherpas.com\/content\/uploads\/2023\/11\/la-composition-de-lair-hulk-1.gif\" alt=\"Hulk envoie valser Thor.\" class=\"wp-image-267933\" style=\"width:540px;height:auto\" \/><\/figure>\n<\/div>\n\n\n<p>\u200b\ud83d\udc49<strong> La pression atmosph\u00e9rique se mesure avec un manom\u00e8tre<\/strong>, un outil qu\u2019on utilise pour d\u00e9terminer le niveau de pression dans une installation de chauffage. Ce qu\u2019on te conseille d\u2019absolument retenir, c\u2019est qu\u2019il existe deux unit\u00e9s de mesure :<\/p>\n\n\n<section class=\"you-know\">\n                <div class=\"you-know__title\"><\/div>\n                        <div class=\"you-know__text\">\n            <ul>\n<li>le Pascal (Pa), l\u2019unit\u00e9 de pression du Syst\u00e8me International,<\/li>\n<li>et le bar ou le mbar, l\u2019unit\u00e9 de pression courante.<\/li>\n<\/ul>\n\n        <\/div>\n              <\/section>\n\n\n\n<p>\u200b\ud83d\udccdSi tu es curieux, sache que :<\/p>\n\n\n<section class=\"you-know\">\n                <div class=\"you-know__title\"><\/div>\n                        <div class=\"you-know__text\">\n            <ul>\n<li>1 Pa = 1 <a href=\"https:\/\/sherpas.com\/blog\/isaac-newton\/\">newton<\/a> \/ m\u00b2 ;<\/li>\n<li>1 newton (N) \u00e9quivaut \u00e0 0,102 kg ;<\/li>\n<li>1 bar = 100 000 Pa ou 1000 hPA.<\/li>\n<\/ul>\n\n        <\/div>\n              <\/section>\n\n\n\n<p>Pour te donner un exemple, la pression atmosph\u00e9rique moyenne du niveau de la mer est de 1 013, 25 hPa, soit 760 mmHg. Le symbole mmHg renvoie au millim\u00e8tre de mercure. Cette valeur est <strong>consid\u00e9r\u00e9e comme une mesure standard<\/strong>, elle n\u2019est ni basse, ni \u00e9lev\u00e9e.<\/p>\n\n\n\n<p>\u200b\ud83d\udc49<strong> <\/strong>En v\u00e9rit\u00e9,<strong> la pression atmosph\u00e9rique varie naturellement <\/strong>en fonction des conditions m\u00e9t\u00e9orologiques locales. Si une perturbation approchait (comme une temp\u00eate) ou que l\u2019altitude \u00e9tait plus \u00e9lev\u00e9e (comme en montagne), la valeur mentionn\u00e9e changerait en cons\u00e9quence.<\/p>\n\n\n<section class=\"read-also\">\n    <p class=\"read-also__title\">\u00c0 lire aussi<\/p>\n            <div class=\"read-also__list\">\n            <p>\ud83c\udf31 <a href=\"https:\/\/sherpas.com\/blog\/photosynthese\/\">Photosynth\u00e8se<\/a> : d\u00e9finition et utilit\u00e9 !<\/p>\n\n        <\/div>\n    <\/section>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"la-masse-et-le-volume-de-lair\">La masse et le volume de l\u2019air\u200b \ud83c\udf2c\ufe0f<\/h3>\n\n\n\n<p>Comme tous les gaz, <strong>l\u2019air poss\u00e8de une masse<\/strong>. Bien s\u00fbr, tu n\u2019as pas l\u2019impression de constamment porter un poids sur tes \u00e9paules lorsque tu manges tes p\u00e2tes \u00e0 la bolognaise (merci la gravit\u00e9\u200b \ud83e\udee0), mais \u00e7a ne veut pas dire que l\u2019air n\u2019a aucune masse.<\/p>\n\n\n<section class=\"you-know\">\n                <div class=\"you-know__title\"><p>\u200b\ud83e\uddee Quelques chiffres<\/p>\n<\/div>\n                        <div class=\"you-know__text\">\n            <ul>\n<li>La masse d&rsquo;un litre d&rsquo;air est de 1,3 g.<\/li>\n<li>Sa masse volumique est de 1,3 g\/L.<\/li>\n<\/ul>\n\n        <\/div>\n              <\/section>\n\n\n\n<p>\u200b\ud83d\udc49<strong> <\/strong>Quand tu gonfles ton ballon \u00e0 la plage par exemple, tu vois qu\u2019il change d\u2019aspect. Pourquoi\u202f? Parce que sa masse augmente ! Le responsable de ce changement, c\u2019est l\u2019air.<\/p>\n\n\n<section class=\"read-also\">\n    <p class=\"read-also__title\">\u00c0 lire aussi<\/p>\n            <div class=\"read-also__list\">\n            <p>\ud83e\uddd9\u200d\u2640\ufe0f 10 conseils magiques pour le <a href=\"https:\/\/sherpas.com\/blog\/conseils-bac-physique-chimie\/\">bac de physique-chimie<\/a> !<\/p>\n\n        <\/div>\n    <\/section>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"cas-pratique\">Cas pratique\u200b \ud83e\uddd1\u200d\ud83d\udd2c<\/h4>\n\n\n\n<p>Imaginons que tu doives <strong>mesurer la masse d\u2019un litre et demi d\u2019air <\/strong>en utilisant un ballon gonfl\u00e9 et la technique du \u00ab d\u00e9placement d\u2019eau \u00bb. En physique-chimie, cette m\u00e9thode sert \u00e0 mesurer le volume d\u2019un objet \u00e0 l\u2019aide d\u2019un r\u00e9cipient rempli d\u2019eau et d\u2019une \u00e9prouvette.<\/p>\n\n\n\n<p>\u200b\ud83d\udccd<strong> <\/strong>Voici un r\u00e9cap des \u00e9tapes cl\u00e9s de cette exp\u00e9rience :<\/p>\n\n\n\n<p><\/p>\n\n\n\n<table id=\"tablepress-2196\" class=\"tablepress tablepress-id-2196\">\n<tbody class=\"row-striping row-hover\">\n<tr class=\"row-1\">\n\t<td class=\"column-1\">Tu mesures la masse du ballon avec une balance (108,4 g).<\/td>\n<\/tr>\n<tr class=\"row-2\">\n\t<td class=\"column-1\">Tu retires le volume d\u2019air donn\u00e9, soit 1,5 litre.<br \/>\n<\/td>\n<\/tr>\n<tr class=\"row-3\">\n\t<td class=\"column-1\">Tu mesures de nouveau la masse du ballon (106,9 g).<br \/>\n<\/td>\n<\/tr>\n<tr class=\"row-4\">\n\t<td class=\"column-1\">Tu soustrais la masse finale \u00e0 la masse initiale.<br \/>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<!-- #tablepress-2196 from cache -->\n\n\n\n<p>\u200b\ud83d\udc49<strong> <\/strong>Comme 108, 4 &#8211; 106, 9 donne 1,5 g, \u00e7a signifie que <strong>1,5 litre d\u2019air p\u00e8se 1,5 g<\/strong>.<\/p>\n\n\n<section class=\"read-also\">\n    <p class=\"read-also__title\">\u00c0 lire aussi<\/p>\n            <div class=\"read-also__list\">\n            <p>\ud83c\udf0a Tout savoir sur la <a href=\"https:\/\/sherpas.com\/blog\/masse-volumique-eau\/\">masse volumique de l\u2019eau<\/a> !<\/p>\n\n        <\/div>\n    <\/section>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"recapitulatif\">\u2705 R\u00e9capitulatif<\/h2>\n\n\n<section class=\"you-know\">\n                <div class=\"you-know__title\"><\/div>\n                        <div class=\"you-know__text\">\n            <p>\ud83d\udccc Le terme \u00ab air \u00bb d\u00e9signe un fluide gazeux incolore, inodore et invisible.<\/p>\n<p>\u200b\ud83d\udccc L\u2019air n\u2019est ni une mati\u00e8re liquide, ni une mati\u00e8re solide.<\/p>\n<p>\u200b\ud83d\udccc L\u2019air n&rsquo;est pas un corps pur, c\u2019est un m\u00e9lange de diff\u00e9rents constituants.<\/p>\n<p>\u200b\ud83d\udccc Cette mati\u00e8re constitue l&rsquo;atmosph\u00e8re terrestre, dont la troposph\u00e8re.<\/p>\n<p>\u200b\ud83d\udccc Elle joue un r\u00f4le dans la photosynth\u00e8se et l&rsquo;\u00e9vaporation des oc\u00e9ans.<\/p>\n<p>\u200b\ud83d\udccc Lavoisier a \u00e9t\u00e9 le premier \u00e0 montrer que l&rsquo;air poss\u00e8de plusieurs composants.<\/p>\n<p>\u200b\ud83d\udccc L\u2019air comporte 78 % de diazote, 21 % de dioxyg\u00e8ne et 1 % d&rsquo;autres gaz.<\/p>\n<p>\u200b\ud83d\udccc La qualit\u00e9 de l&rsquo;air peut \u00eatre alt\u00e9r\u00e9e par des corps naturels ou polluants.<\/p>\n<p>\u200b\ud83d\udccc La pression atmosph\u00e9rique se mesure avec un manom\u00e8tre.<\/p>\n<p>\u200b\ud83d\udccc Il existe deux unit\u00e9s de mesure courantes : le Pascal (Pa) et le bar.<\/p>\n\n        <\/div>\n              <\/section>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"conclusion\">Conclusion<\/h3>\n\n\n\n<p>Cet article est termin\u00e9, on esp\u00e8re que tu connais \u00e0 pr\u00e9sent<strong> la composition de l\u2019air et le r\u00f4le que joue ce fluide gazeux<\/strong>. Si tu as besoin d\u2019aide en physique et que tu souhaites r\u00e9viser depuis chez toi, tu peux prendre des <a href=\"https:\/\/sherpas.com\/cours\/physique\/online\">cours particuliers de physique en ligne<\/a>. \u00c0 bient\u00f4t !\u200b \ud83d\ude0a<\/p>\n\n\n<div class=\"kk-star-ratings kksr-auto kksr-align-center kksr-valign-bottom\"\n    data-payload='{&quot;align&quot;:&quot;center&quot;,&quot;id&quot;:&quot;267915&quot;,&quot;slug&quot;:&quot;default&quot;,&quot;valign&quot;:&quot;bottom&quot;,&quot;ignore&quot;:&quot;&quot;,&quot;reference&quot;:&quot;auto&quot;,&quot;class&quot;:&quot;&quot;,&quot;count&quot;:&quot;12&quot;,&quot;legendonly&quot;:&quot;&quot;,&quot;readonly&quot;:&quot;&quot;,&quot;score&quot;:&quot;5&quot;,&quot;starsonly&quot;:&quot;&quot;,&quot;best&quot;:&quot;5&quot;,&quot;gap&quot;:&quot;5&quot;,&quot;greet&quot;:&quot;Tu as aim\u00e9 cet article ?&quot;,&quot;legend&quot;:&quot;5\\\/5 - (12 votes)&quot;,&quot;size&quot;:&quot;24&quot;,&quot;title&quot;:&quot;La composition de l\u2019air : fiche de physique-chimie \ud83d\udca8&quot;,&quot;width&quot;:&quot;142.5&quot;,&quot;_legend&quot;:&quot;{score}\\\/{best} - ({count} {votes})&quot;,&quot;font_factor&quot;:&quot;1.25&quot;}'>\n            \n<div class=\"kksr-stars\">\n    \n<div class=\"kksr-stars-inactive\">\n            <div class=\"kksr-star\" data-star=\"1\" style=\"padding-right: 5px\">\n            \n\n<div class=\"kksr-icon\" style=\"width: 24px; height: 24px;\"><\/div>\n        <\/div>\n            <div class=\"kksr-star\" data-star=\"2\" style=\"padding-right: 5px\">\n            \n\n<div class=\"kksr-icon\" style=\"width: 24px; height: 24px;\"><\/div>\n        <\/div>\n            <div class=\"kksr-star\" data-star=\"3\" style=\"padding-right: 5px\">\n            \n\n<div class=\"kksr-icon\" style=\"width: 24px; height: 24px;\"><\/div>\n        <\/div>\n            <div class=\"kksr-star\" data-star=\"4\" style=\"padding-right: 5px\">\n            \n\n<div class=\"kksr-icon\" style=\"width: 24px; height: 24px;\"><\/div>\n        <\/div>\n            <div class=\"kksr-star\" data-star=\"5\" style=\"padding-right: 5px\">\n            \n\n<div class=\"kksr-icon\" style=\"width: 24px; height: 24px;\"><\/div>\n        <\/div>\n    <\/div>\n    \n<div class=\"kksr-stars-active\" style=\"width: 142.5px;\">\n            <div class=\"kksr-star\" style=\"padding-right: 5px\">\n            \n\n<div class=\"kksr-icon\" style=\"width: 24px; height: 24px;\"><\/div>\n        <\/div>\n            <div class=\"kksr-star\" style=\"padding-right: 5px\">\n            \n\n<div class=\"kksr-icon\" style=\"width: 24px; height: 24px;\"><\/div>\n        <\/div>\n            <div class=\"kksr-star\" style=\"padding-right: 5px\">\n            \n\n<div class=\"kksr-icon\" style=\"width: 24px; height: 24px;\"><\/div>\n        <\/div>\n            <div class=\"kksr-star\" style=\"padding-right: 5px\">\n            \n\n<div class=\"kksr-icon\" style=\"width: 24px; height: 24px;\"><\/div>\n        <\/div>\n            <div class=\"kksr-star\" style=\"padding-right: 5px\">\n            \n\n<div class=\"kksr-icon\" style=\"width: 24px; height: 24px;\"><\/div>\n        <\/div>\n    <\/div>\n<\/div>\n                \n\n<div class=\"kksr-legend\" style=\"font-size: 19.2px;\">\n            5\/5 - (12 votes)    <\/div>\n    <\/div>\n","protected":false},"excerpt":{"rendered":"<p>As-tu d\u00e9j\u00e0 r\u00e9fl\u00e9chi \u00e0 ce que tu respires\u202f? Chaque jour, on inhale et exhale de l\u2019air, un \u00e9l\u00e9ment (&#8230;)<\/p>\n","protected":false},"author":329,"featured_media":267935,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"category":[803,812],"tag":[315,77,770],"class_list":["post-267915","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-apprendre-matiere","category-physique-chimie-2","tag-brevet","tag-college","tag-fiche-revision"],"acf":[],"_links":{"self":[{"href":"https:\/\/sherpas.com\/blog\/wp-json\/wp\/v2\/posts\/267915","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/sherpas.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/sherpas.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/sherpas.com\/blog\/wp-json\/wp\/v2\/users\/329"}],"replies":[{"embeddable":true,"href":"https:\/\/sherpas.com\/blog\/wp-json\/wp\/v2\/comments?post=267915"}],"version-history":[{"count":0,"href":"https:\/\/sherpas.com\/blog\/wp-json\/wp\/v2\/posts\/267915\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/sherpas.com\/blog\/wp-json\/wp\/v2\/media\/267935"}],"wp:attachment":[{"href":"https:\/\/sherpas.com\/blog\/wp-json\/wp\/v2\/media?parent=267915"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/sherpas.com\/blog\/wp-json\/wp\/v2\/category?post=267915"},{"taxonomy":"tag","embeddable":true,"href":"https:\/\/sherpas.com\/blog\/wp-json\/wp\/v2\/tag?post=267915"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}