{"id":66870,"date":"2026-10-13T10:01:38","date_gmt":"2026-10-13T07:01:38","guid":{"rendered":"https:\/\/wpcalc.com\/en\/?p=66870"},"modified":"2026-10-13T10:01:38","modified_gmt":"2026-10-13T07:01:38","slug":"avogadros-law-calculator","status":"publish","type":"post","link":"https:\/\/wpcalc.com\/en\/chemistry\/avogadros-law-calculator\/","title":{"rendered":"Avogadro's Law Calculator"},"content":{"rendered":"<section class=\"not-prose calculator-box\" aria-labelledby=\"calculator-title\"><div class=\"flex items-baseline sm:items-center justify-between gap-2 sm:gap-3\"><div class=\"flex flex-col sm:flex-row sm:items-center gap-2\"><span class=\"icon icon-calculator text-primary-700! text-base! dark:text-primary-300!\" aria-hidden=\"true\"><\/span><h2 id=\"calculator-title\" class=\"text-lg font-display font-bold\">Find the Missing Volume or Amount of Gas<\/h2><\/div><div class=\"calcdash-favorite group\">\n  <button type=\"button\" class=\"favorite\" id=\"favorite\" data-favorite-id=\"66870\" data-favorite-title=\"Avogadro&#039;s Law\" data-favorite-url=\"https:\/\/wpcalc.com\/en\/chemistry\/avogadros-law-calculator\/\" data-favorite-excerpt=\"Calculate the missing volume or amount of gas using Avogadro&#039;s law. Enter the initial volume and amount, plus the new amount or new volume, and get the result with full steps.\" aria-label=\"Add to Favorites\" data-favorite-icon=\"icon icon-wind-2\">\n    <span class=\"icon icon-shape-star-empty\" aria-hidden=\"true\"><\/span>\n  <\/button>\n  <div class=\"calcdash-favorite__tip\" aria-hidden=\"true\">\n   <span class=\"favorite-tooltip\" id=\"favorite-tooltip\"><\/span>\n  <\/div>\n  <span class=\"sr-only\" role=\"status\" id=\"favorite-status\"><\/span>\n<\/div><\/div><form action=\"https:\/\/wpcalc.com\/en\/chemistry\/avogadros-law-calculator\/\" method=\"POST\" class=\"calculator\" id=\"calculator-66870\" data-post=\"66870\"><fieldset class=\"fieldset-input is-2\"><legend class=\"sr-only\">Input Fields<\/legend><div class=\"field is-single\" id=\"input-1\"><label for=\"field-1\">Solve for<\/label><div class=\"grid grid-cols-1\"><select id=\"field-1\" name=\"solve_for\"><option value=\"v2\" selected>Final volume (V\u2082)<\/option><option value=\"n2\">Final amount (n\u2082)<\/option><\/select><svg class=\"pointer-events-none col-start-1 row-start-1 mr-2 size-5 self-center justify-self-end text-gray-500 sm:size-4\" viewBox=\"0 0 16 16\" fill=\"currentColor\" aria-hidden=\"true\" data-slot=\"icon\">\n              <path fill-rule=\"evenodd\" d=\"M4.22 6.22a.75.75 0 0 1 1.06 0L8 8.94l2.72-2.72a.75.75 0 1 1 1.06 1.06l-3.25 3.25a.75.75 0 0 1-1.06 0L4.22 7.28a.75.75 0 0 1 0-1.06Z\" clip-rule=\"evenodd\" \/>\n            <\/svg><\/div><\/div><div class=\"field has-term\" id=\"input-2\"><label for=\"field-2\">Initial Volume (V\u2081)<\/label><div class=\"term\">V\u2081<\/div>  <div class=\"absolute bottom-0 left-16 top-8 w-2 h-0.5 bg-blue-500\"><\/div><div class=\"field-group\"><input type=\"text\" name=\"initial_volume_v\" id=\"field-2\" aria-describedby=\"calc-info-2\" data-number inputmode=\"decimal\" autocomplete=\"off\" spellcheck=\"false\" placeholder=\"e.g. 2\" min=\"0\" value=\"2\"\/><div class=\"grid grid-cols-1\"><select id=\"field-3\" name=\"unit\" aria-label=\"Unit\"><option value=\"L\" selected>L<\/option><option value=\"mL\">mL<\/option><option value=\"cm3\">cm\u00b3<\/option><option value=\"m3\">m\u00b3<\/option><option value=\"ft3\">ft\u00b3<\/option><option value=\"gal\">gal (US)<\/option><\/select><svg class=\"pointer-events-none col-start-1 row-start-1 mr-2 size-5 self-center justify-self-end text-gray-500 sm:size-4\" viewBox=\"0 0 16 16\" fill=\"currentColor\" aria-hidden=\"true\" data-slot=\"icon\">\n              <path fill-rule=\"evenodd\" d=\"M4.22 6.22a.75.75 0 0 1 1.06 0L8 8.94l2.72-2.72a.75.75 0 1 1 1.06 1.06l-3.25 3.25a.75.75 0 0 1-1.06 0L4.22 7.28a.75.75 0 0 1 0-1.06Z\" clip-rule=\"evenodd\" \/>\n            <\/svg><\/div><\/div><small id=\"calc-info-2\">Volume of the gas at the start.<\/small><\/div><div class=\"field has-term\" id=\"input-3\"><label for=\"field-4\">Initial Amount (n\u2081)<\/label><div class=\"term\">n\u2081<\/div>  <div class=\"absolute bottom-0 left-16 top-8 w-2 h-0.5 bg-blue-500\"><\/div><div class=\"field-group\"><input type=\"text\" name=\"initial_amount_n\" id=\"field-4\" aria-describedby=\"calc-info-4\" data-number inputmode=\"decimal\" autocomplete=\"off\" spellcheck=\"false\" placeholder=\"e.g. 0.5\" min=\"0\" value=\"0.5\"\/><div class=\"grid grid-cols-1\"><select id=\"field-5\" name=\"unit\" aria-label=\"Unit\"><option value=\"mol\" selected>mol<\/option><option value=\"mmol\">mmol<\/option><option value=\"kmol\">kmol<\/option><\/select><svg class=\"pointer-events-none col-start-1 row-start-1 mr-2 size-5 self-center justify-self-end text-gray-500 sm:size-4\" viewBox=\"0 0 16 16\" fill=\"currentColor\" aria-hidden=\"true\" data-slot=\"icon\">\n              <path fill-rule=\"evenodd\" d=\"M4.22 6.22a.75.75 0 0 1 1.06 0L8 8.94l2.72-2.72a.75.75 0 1 1 1.06 1.06l-3.25 3.25a.75.75 0 0 1-1.06 0L4.22 7.28a.75.75 0 0 1 0-1.06Z\" clip-rule=\"evenodd\" \/>\n            <\/svg><\/div><\/div><small id=\"calc-info-4\">Amount of gas at the start (moles).<\/small><\/div><div class=\"field has-term\" id=\"input-4\"><label for=\"field-6\">Final Amount (n\u2082)<\/label><div class=\"term\">n\u2082<\/div>  <div class=\"absolute bottom-0 left-16 top-8 w-2 h-0.5 bg-blue-500\"><\/div><div class=\"field-group\"><input type=\"text\" name=\"final_amount_n\" id=\"field-6\" aria-describedby=\"calc-info-6\" data-number inputmode=\"decimal\" autocomplete=\"off\" spellcheck=\"false\" placeholder=\"e.g. 1.5\" min=\"0\" value=\"1.5\"\/><div class=\"grid grid-cols-1\"><select id=\"field-7\" name=\"unit\" aria-label=\"Unit\"><option value=\"mol\" selected>mol<\/option><option value=\"mmol\">mmol<\/option><option value=\"kmol\">kmol<\/option><\/select><svg class=\"pointer-events-none col-start-1 row-start-1 mr-2 size-5 self-center justify-self-end text-gray-500 sm:size-4\" viewBox=\"0 0 16 16\" fill=\"currentColor\" aria-hidden=\"true\" data-slot=\"icon\">\n              <path fill-rule=\"evenodd\" d=\"M4.22 6.22a.75.75 0 0 1 1.06 0L8 8.94l2.72-2.72a.75.75 0 1 1 1.06 1.06l-3.25 3.25a.75.75 0 0 1-1.06 0L4.22 7.28a.75.75 0 0 1 0-1.06Z\" clip-rule=\"evenodd\" \/>\n            <\/svg><\/div><\/div><small id=\"calc-info-6\">New amount of gas; the final volume is calculated.<\/small><\/div><div class=\"field has-term\" id=\"input-5\" hidden><label for=\"field-8\">Final Volume (V\u2082)<\/label><div class=\"term\">V\u2082<\/div>  <div class=\"absolute bottom-0 left-16 top-8 w-2 h-0.5 bg-blue-500\"><\/div><div class=\"field-group\"><input type=\"text\" name=\"final_volume_v\" id=\"field-8\" aria-describedby=\"calc-info-8\" data-number inputmode=\"decimal\" autocomplete=\"off\" spellcheck=\"false\" placeholder=\"e.g. 6\" min=\"0\" value=\"6\"\/><div class=\"grid grid-cols-1\"><select id=\"field-9\" name=\"unit\" aria-label=\"Unit\"><option value=\"L\" selected>L<\/option><option value=\"mL\">mL<\/option><option value=\"cm3\">cm\u00b3<\/option><option value=\"m3\">m\u00b3<\/option><option value=\"ft3\">ft\u00b3<\/option><option value=\"gal\">gal (US)<\/option><\/select><svg class=\"pointer-events-none col-start-1 row-start-1 mr-2 size-5 self-center justify-self-end text-gray-500 sm:size-4\" viewBox=\"0 0 16 16\" fill=\"currentColor\" aria-hidden=\"true\" data-slot=\"icon\">\n              <path fill-rule=\"evenodd\" d=\"M4.22 6.22a.75.75 0 0 1 1.06 0L8 8.94l2.72-2.72a.75.75 0 1 1 1.06 1.06l-3.25 3.25a.75.75 0 0 1-1.06 0L4.22 7.28a.75.75 0 0 1 0-1.06Z\" clip-rule=\"evenodd\" \/>\n            <\/svg><\/div><\/div><small id=\"calc-info-8\">New volume of the gas; the final amount is calculated.<\/small><\/div><\/fieldset><div class=\"buttons\"><button type=\"submit\" data-text=\"Re-Calculate\" id=\"calculate-button\" data-post=\"66870\">Calculate<\/button><button type=\"reset\">Reset<\/button><\/div><div class=\"field is-checkbox hidden!\" id=\"field-auto-calc\"><input type=\"checkbox\" id=\"auto-calc\"><label for=\"auto-calc\">Calculate automatically<\/label><small>If enabled, the result will update automatically when you change any value.<\/small><\/div><div class=\"fieldset-result is-hidden\" aria-labelledby=\"result-title\" aria-live=\"polite\" role=\"region\"> <h3 class=\"result-title bg-gradient-to-r from-primary-50 to-gray-50 dark:from-primary-900 dark:to-gray-800\" id=\"result-title\"><span class=\"icon icon-s-pulse\" aria-hidden=\"true\"><\/span> Avogadro&#039;s Law Results<\/h3><div class=\"result-box\"><div class=\"field-result\" id=\"output-1\"><span class=\"field-title\"><span>Final Volume (V\u2082)<\/span><span class=\"result-term\">V\u2082<\/span><\/span><span class=\"field-value\" id=\"result-1\"><\/span><button type=\"button\" class=\"copy-result\" data-tooltip=\"Copy Result\" aria-label=\"Copy Result\"><span class=\"copy-icon icon icon-document-copy\" aria-hidden=\"true\"><\/span><\/button><\/div><div class=\"field-result\" id=\"output-2\"><span class=\"field-title\"><span>Final Amount (n\u2082)<\/span><span class=\"result-term\">n\u2082<\/span><\/span><span class=\"field-value\" id=\"result-2\"><\/span><button type=\"button\" class=\"copy-result\" data-tooltip=\"Copy Result\" aria-label=\"Copy Result\"><span class=\"copy-icon icon icon-document-copy\" aria-hidden=\"true\"><\/span><\/button><\/div><div class=\"field-result is-column\" id=\"output-3\"><span class=\"field-title\"><span>Calculation Steps<\/span><\/span><span class=\"field-value\" id=\"result-3\"><\/span><button type=\"button\" class=\"copy-result\" data-tooltip=\"Copy Result\" aria-label=\"Copy Result\"><span class=\"copy-icon icon icon-document-copy\" aria-hidden=\"true\"><\/span><\/button><\/div><div class=\"field-result is-column\" id=\"output-4\"><span class=\"field-title\"><span>About Avogadro&#039;s Law<\/span><\/span><span class=\"field-value\" id=\"result-4\"><\/span><button type=\"button\" class=\"copy-result\" data-tooltip=\"Copy Result\" aria-label=\"Copy Result\"><span class=\"copy-icon icon icon-document-copy\" aria-hidden=\"true\"><\/span><\/button><\/div><\/div><div class=\"result-actions\"><button type=\"button\" class=\"copy-link\"><svg viewBox=\"0 0 20 20\" fill=\"currentColor\" aria-hidden=\"true\"><path d=\"M12.232 4.232a2.5 2.5 0 0 1 3.536 3.536l-1.225 1.224a.75.75 0 0 0 1.061 1.06l1.224-1.224a4 4 0 0 0-5.656-5.656l-3 3a4 4 0 0 0 .225 5.865.75.75 0 0 0 .977-1.138 2.5 2.5 0 0 1-.142-3.667l3-3Z\"\/><path d=\"M11.603 7.963a.75.75 0 0 0-.977 1.138 2.5 2.5 0 0 1 .142 3.667l-3 3a2.5 2.5 0 0 1-3.536-3.536l1.225-1.224a.75.75 0 0 0-1.061-1.06l-1.224 1.224a4 4 0 1 0 5.656 5.656l3-3a4 4 0 0 0-.225-5.865Z\"\/><\/svg><span class=\"copy-link__text\">Copy link to this calculation<\/span><\/button><span class=\"sr-only\" role=\"status\" id=\"copy-link-status\"><\/span><\/div><\/div><a href=\"#respond\" class=\"hidden transition-opacity duration-300 opacity-0 w-50 text-sm justify-center items-center gap-2 px-4 py-2 rounded bg-gray-200 text-gray-700 hover:bg-gray-300\" id=\"leave-comment\"><span class=\"icon icon-comments\" aria-hidden=\"true\"><\/span>Leave a Comment<\/a><\/form><\/section><section id=\"calc-reactions\" class=\"not-prose hidden my-12 bg-gradient-to-r from-primary-50 to-gray-50 border border-indigo-100 rounded-xl px-6 py-4 shadow-sm\" data-post=\"66870\" aria-live=\"polite\" aria-labelledby=\"calc-reactions-title\"><p id=\"calc-reactions-title\" class=\"text-sm text-gray-500 text-center mb-2\">How did this result make you feel?<\/p><div role=\"group\" aria-labelledby=\"calc-reactions-title\" class=\"grid grid-cols-3 sm:flex sm:flex-row sm:justify-around gap-4 sm:items-center sm:flex-wrap\"><button type=\"button\" aria-pressed=\"false\" class=\"reaction-btn flex flex-col items-center gap-1 text-sm text-gray-700 hover:text-primary-600 cursor-pointer transition-transform hover:scale-105\" data-reaction=\"like\"><span class=\"reaction-count\" data-reaction-count=\"like\">0<\/span><span class=\"reaction text-3xl\" aria-hidden=\"true\">\ud83d\ude00 <\/span><span class=\"reaction-description font-medium\">Like <\/span><\/button><button type=\"button\" aria-pressed=\"false\" class=\"reaction-btn flex flex-col items-center gap-1 text-sm text-gray-700 hover:text-primary-600 cursor-pointer transition-transform hover:scale-105\" data-reaction=\"helpful\"><span class=\"reaction-count\" data-reaction-count=\"helpful\">0<\/span><span class=\"reaction text-3xl\" aria-hidden=\"true\">\ud83d\udca1 <\/span><span class=\"reaction-description font-medium\">Helpful <\/span><\/button><button type=\"button\" aria-pressed=\"false\" class=\"reaction-btn flex flex-col items-center gap-1 text-sm text-gray-700 hover:text-primary-600 cursor-pointer transition-transform hover:scale-105\" data-reaction=\"confused\"><span class=\"reaction-count\" data-reaction-count=\"confused\">0<\/span><span class=\"reaction text-3xl\" aria-hidden=\"true\">\ud83d\ude15 <\/span><span class=\"reaction-description font-medium\">Confused <\/span><\/button><button type=\"button\" aria-pressed=\"false\" class=\"reaction-btn flex flex-col items-center gap-1 text-sm text-gray-700 hover:text-primary-600 cursor-pointer transition-transform hover:scale-105\" data-reaction=\"disappointed\"><span class=\"reaction-count\" data-reaction-count=\"disappointed\">0<\/span><span class=\"reaction text-3xl\" aria-hidden=\"true\">\ud83d\ude1e <\/span><span class=\"reaction-description font-medium\">Disappointed <\/span><\/button><button type=\"button\" aria-pressed=\"false\" class=\"reaction-btn flex flex-col items-center gap-1 text-sm text-gray-700 hover:text-primary-600 cursor-pointer transition-transform hover:scale-105\" data-reaction=\"inaccurate\"><span class=\"reaction-count\" data-reaction-count=\"inaccurate\">0<\/span><span class=\"reaction text-3xl\" aria-hidden=\"true\">\u274c <\/span><span class=\"reaction-description font-medium\">Inaccurate <\/span><\/button><\/div><div id=\"reaction-message\" class=\"hidden mt-8 rounded-md border border-primary-100 bg-white\/50 backdrop-blur-sm px-4 py-2 text-sm text-center shadow-sm\"><\/div><\/section><div class=\"calcdash-ad not-prose calcdash-ad--calc_result calcdash-ad--in-article\"><ins class=\"adsbygoogle\" style=\"display:block\" data-ad-client=\"ca-pub-1721569815777345\" data-ad-slot=\"6317458308\" data-ad-layout=\"in-article\" data-ad-format=\"fluid\"><\/ins><script>(adsbygoogle = window.adsbygoogle || []).push({});<\/script><\/div>\n<style id=\"wpcoderpro-inline-1\">.formula-box {\r\n\tborder-bottom: none !important;\r\n}<\/style><section class=\"formula-box\" aria-labelledby=\"formula-title\">\r\n\t<div id=\"formula-title\" class=\"not-prose font-display mb-4\"><span class=\"icon icon-formula\" aria-hidden=\"true\"><\/span><h2>Avogadro's Law Formula<\/h2><\/div>\r\n\t<figure class=\"not-prose formula\">\r\n\t\t<figcaption class=\"formula-title\">Formula<\/figcaption>\r\n\t\t<div class=\"text-base text-gray-800\" id=\"formula\">\n\\[ \\frac{V_1}{n_1} = \\frac{V_2}{n_2} \\]\n<\/div>\r\n\t<\/figure>\r\n\t<\/p>\n<p><strong>Where:<\/strong><\/p>\n<ul>\n<li>\\(V_1\\), \\(V_2\\) \u2014 initial and final volume of the gas<\/li>\n<li>\\(n_1\\), \\(n_2\\) \u2014 initial and final amount of gas (moles)<\/li>\n<\/ul>\n<p>The formula states that at constant temperature and pressure, the volume of a gas is directly proportional to the number of moles. Rearranged, it gives the missing value directly: \\(V_2 = V_1 \\cdot \\frac{n_2}{n_1}\\) or \\(n_2 = n_1 \\cdot \\frac{V_2}{V_1}\\).<\/p>\n<p>\r\n<\/section>\n<style id=\"wpcoderpro-inline-459\">.calculation-box {\r\n\tborder-bottom: none !important;\r\n}<\/style><section id=\"calculation\" class=\"calculation-box\" aria-labelledby=\"calculation-title\">\r\n\t<div id=\"calculation-title\" class=\"not-prose font-display\"><span class=\"icon icon-unordered-list\" aria-hidden=\"true\"><\/span><h2>Avogadro's Law \u2013 Calculation Example<\/h2><\/div>\r\n\r\n<\/p>\n<p><strong>Example:<\/strong> a gas occupies 2 L in a flexible container at fixed temperature and pressure, containing 0.5 mol of gas. More gas is added until the sample holds 1.5 mol. What is the new volume?<\/p>\n<p>\\[ V_2 = V_1 \\cdot \\frac{n_2}{n_1} = 2\\ \\text{L} \\cdot \\frac{1.5\\ \\text{mol}}{0.5\\ \\text{mol}} = 6\\ \\text{L} \\]<\/p>\n<p><strong>Result:<\/strong> the final volume is 6 L. Tripling the amount of gas (from 0.5 mol to 1.5 mol) triples the volume, exactly as Avogadro's law predicts.<\/p>\n<p>\n\r\n<\/section>\n<h2>How to Use the Calculator<\/h2>\n<ol>\n<li>Open the <strong>Solve for<\/strong> dropdown and choose whether you want the <strong>Final volume (V\u2082)<\/strong> or the <strong>Final amount (n\u2082)<\/strong>. The field for the value you already know appears; the other one is hidden.<\/li>\n<li>Enter the <strong>Initial Volume (V\u2081)<\/strong> and pick its unit (L, mL, cm\u00b3, m\u00b3, ft\u00b3 or US gallons).<\/li>\n<li>Enter the <strong>Initial Amount (n\u2081)<\/strong> in mol, mmol or kmol.<\/li>\n<li>Enter the known final value: <strong>Final Amount (n\u2082)<\/strong> if you are solving for volume, or <strong>Final Volume (V\u2082)<\/strong> with its unit if you are solving for the amount.<\/li>\n<li>Read the result, the step-by-step calculation, and the verification that \\(V_1\/n_1 = V_2\/n_2\\).<\/li>\n<\/ol>\n<p>All unit conversions are handled automatically \u2014 you can enter V\u2081 in litres and V\u2082 in cubic feet, and the answer for n\u2082 comes back in the unit you chose for n\u2081.<\/p>\n<h2>What Is Avogadro's Law?<\/h2>\n<p>Avogadro's law, proposed by Amedeo Avogadro in 1811, states that <em>equal volumes of all gases at the same temperature and pressure contain equal numbers of molecules<\/em>. An equivalent statement is that the volume of a gas sample is directly proportional to the amount of gas (in moles) when temperature and pressure are held constant. Doubling the moles of gas doubles the volume; removing half the gas halves the volume.<\/p>\n<p>The law is one of the cornerstone relationships of the <em>ideal gas law<\/em>, \\(PV = nRT\\). If pressure \\(P\\) and temperature \\(T\\) are constant, solving for \\(V\\) gives \\(V = \\frac{nRT}{P}\\), so \\(V\/n = \\text{constant}\\). Avogadro's law is simply the comparison of this ratio between two states of the same gas under the same conditions.<\/p>\n<p>A useful consequence is the <strong>molar volume<\/strong>: one mole of any ideal gas occupies the same volume at a given temperature and pressure. At STP (0 \u00b0C, 1 atm) that volume is 22.414 L; at 25 \u00b0C and 1 bar it is 24.789 L. This makes it possible to convert between gas volumes and moles without weighing the gas \u2014 a routine step in stoichiometry, gas collection over water, and industrial gas measurements.<\/p>\n<p>When interpreting your result, remember that the proportionality works in both directions: if the calculator reports a factor of 3 between \\(n_2\\) and \\(n_1\\), the volume also changed by a factor of 3. If your calculated molar volume \\(V\/n\\) is far from 22\u201325 L\/mol at near-ambient conditions, double-check the inputs \u2014 it may signal a unit or decimal error.<\/p>\n<h2>Reference Values<\/h2>\n<table>\n<thead>\n<tr>\n<th>Conditions<\/th>\n<th>Molar volume of an ideal gas<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>0 \u00b0C, 1 atm (STP)<\/td>\n<td>22.414 L\/mol<\/td>\n<\/tr>\n<tr>\n<td>25 \u00b0C, 1 atm<\/td>\n<td>24.465 L\/mol<\/td>\n<\/tr>\n<tr>\n<td>25 \u00b0C, 1 bar (SATP)<\/td>\n<td>24.789 L\/mol<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<h2>Assumptions, Limitations and Tips<\/h2>\n<ul>\n<li><strong>Ideal-gas behaviour.<\/strong> Avogadro's law assumes gas particles have negligible volume and exert no intermolecular forces. Real gases follow it closely at low pressure and temperatures well above their boiling point, but deviate at high pressure or near condensation. For dense gases, the <a href=\"https:\/\/wpcalc.com\/en\/chemistry\/van-der-waals-equation-calculator\/\">Van der Waals Equation Calculator<\/a> gives a more accurate description.<\/li>\n<li><strong>Constant temperature and pressure.<\/strong> The law applies only when both \\(T\\) and \\(P\\) are the same before and after the change. A flexible container (piston or balloon) open to constant external pressure is the typical setup. If temperature also changes, use the combined or ideal gas law instead.<\/li>\n<li><strong>Amount means moles of gas only.<\/strong> Adding a liquid or solid to the container does not change \\(n\\); only gaseous species count. Dissolved gas evolving from solution does count.<\/li>\n<li><strong>Consistent units.<\/strong> Because the law is a ratio, \\(V_1\\) and \\(V_2\\) just need the same unit, and \\(n_1\\) and \\(n_2\\) the same unit \u2014 the calculator handles this for you, including mixed units.<\/li>\n<li><strong>Number of molecules.<\/strong> Multiplying the final amount by the Avogadro constant, \\(N_A = 6.02214076 \\times 10^{23}\\ \\text{mol}^{-1}\\), tells you how many molecules the final sample contains \u2014 the calculator reports this automatically.<\/li>\n<\/ul>\n<p>If your problem involves comparing how fast two gases diffuse rather than how much space they occupy, see the <a href=\"https:\/\/wpcalc.com\/en\/chemistry\/grahams-law-calculator\/\">Graham's Law Calculator<\/a>. For reactions where the amount of gas changes over time, the <a href=\"https:\/\/wpcalc.com\/en\/chemistry\/reaction-half-life-calculator\/\">Reaction Half-Life Calculator<\/a> can help you track \\(n\\) before applying Avogadro's law.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Calculate the missing volume or amount of gas using Avogadro's law. Enter the initial volume and amount, plus the new amount or new volume, and get the result with full steps.<\/p>\n","protected":false},"author":3168,"featured_media":0,"comment_status":"open","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[54],"tags":[55],"class_list":["post-66870","post","type-post","status-publish","format-standard","hentry","category-chemistry","tag-gases"],"acf":[],"_links":{"self":[{"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/posts\/66870","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/users\/3168"}],"replies":[{"embeddable":true,"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/comments?post=66870"}],"version-history":[{"count":1,"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/posts\/66870\/revisions"}],"predecessor-version":[{"id":66872,"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/posts\/66870\/revisions\/66872"}],"wp:attachment":[{"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/media?parent=66870"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/categories?post=66870"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/tags?post=66870"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}