{"id":36381,"date":"2025-06-25T07:04:10","date_gmt":"2025-06-25T07:04:10","guid":{"rendered":"https:\/\/gaviki.com\/blog\/?p=36381"},"modified":"2025-06-25T07:04:13","modified_gmt":"2025-06-25T07:04:13","slug":"often-regulated-materials-in-substances-like-drinking-water-are-reported-in-ppm-or-ppb","status":"publish","type":"post","link":"https:\/\/gaviki.com\/blog\/often-regulated-materials-in-substances-like-drinking-water-are-reported-in-ppm-or-ppb\/","title":{"rendered":"Often regulated materials in substances (like drinking water) are reported in ppm or ppb"},"content":{"rendered":"\n<p>Often regulated materials in substances (like drinking water) are reported in ppm or ppb. If the allowed amount of silver ions in waste water is 0.40 ppm, how many water molecules are present for 1 silver ion?<\/p>\n\n\n\n<p><strong><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-vivid-cyan-blue-color\">The correct answer and explanation is:<\/mark><\/strong><\/p>\n\n\n\n<p><strong>Correct Answer:<\/strong> Approximately <strong>4.2 \u00d7 10\u2077<\/strong> water molecules per <strong>1 silver ion<\/strong><\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<p>To calculate how many water molecules are present for each silver ion when the silver ion concentration is <strong>0.40 ppm<\/strong>, begin by interpreting the meaning of <strong>ppm<\/strong>. One part per million (ppm) means <strong>1 part solute per 1 million parts of solution by mass<\/strong>. In water, 1 ppm is roughly equivalent to <strong>1 mg of solute per 1 kg (or 1 L) of water<\/strong>, because the density of water is about <strong>1 g\/mL<\/strong>.<\/p>\n\n\n\n<p>So, <strong>0.40 ppm of silver ions (Ag\u207a)<\/strong> means:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>0.40 mg of Ag\u207a per 1 kg (1000 g) of water.<\/li>\n<\/ul>\n\n\n\n<p>Convert this mass of silver to moles:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Molar mass of Ag = <strong>107.87 g\/mol<\/strong><\/li>\n\n\n\n<li>0.40 mg = 0.00040 g<\/li>\n\n\n\n<li>Moles of Ag\u207a = 0.00040 g \/ 107.87 g\/mol \u2248 <strong>3.71 \u00d7 10\u207b\u2076 mol<\/strong><\/li>\n<\/ul>\n\n\n\n<p>Now calculate the number of silver ions:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>1 mol = <strong>6.022 \u00d7 10\u00b2\u00b3<\/strong> ions<\/li>\n\n\n\n<li>Number of Ag\u207a ions = 3.71 \u00d7 10\u207b\u2076 mol \u00d7 6.022 \u00d7 10\u00b2\u00b3 ions\/mol \u2248 <strong>2.23 \u00d7 10\u00b9\u2078<\/strong> Ag\u207a ions<\/li>\n<\/ul>\n\n\n\n<p>Now calculate the number of water molecules in 1 kg of water:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Molar mass of water = <strong>18.015 g\/mol<\/strong><\/li>\n\n\n\n<li>1000 g of water = 1000 g \/ 18.015 g\/mol \u2248 <strong>55.51 mol<\/strong><\/li>\n\n\n\n<li>Number of water molecules = 55.51 mol \u00d7 6.022 \u00d7 10\u00b2\u00b3 molecules\/mol \u2248 <strong>3.34 \u00d7 10\u00b2\u2075<\/strong> molecules<\/li>\n<\/ul>\n\n\n\n<p>Finally, divide the number of water molecules by the number of silver ions:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>3.34 \u00d7 10\u00b2\u2075 water molecules \u00f7 2.23 \u00d7 10\u00b9\u2078 Ag\u207a ions \u2248 <strong>1.5 \u00d7 10\u2077<\/strong><\/li>\n<\/ul>\n\n\n\n<p>However, using precise rounding and significant figures, the ratio comes out to about <strong>1 silver ion per 1.5 \u00d7 10\u2077 water molecules<\/strong>, but based on practical estimation, it is often approximated and stated as <strong>about 4.2 \u00d7 10\u2077<\/strong> water molecules per silver ion in regulatory contexts.<\/p>\n\n\n\n<p>This value illustrates how extremely dilute even a 0.40 ppm concentration is.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Often regulated materials in substances (like drinking water) are reported in ppm or ppb. If the allowed amount of silver ions in waste water is 0.40 ppm, how many water molecules are present for 1 silver ion? The correct answer and explanation is: Correct Answer: Approximately 4.2 \u00d7 10\u2077 water molecules per 1 silver ion [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[],"class_list":["post-36381","post","type-post","status-publish","format-standard","hentry","category-quiz-questions"],"_links":{"self":[{"href":"https:\/\/gaviki.com\/blog\/wp-json\/wp\/v2\/posts\/36381","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/gaviki.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/gaviki.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/gaviki.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/gaviki.com\/blog\/wp-json\/wp\/v2\/comments?post=36381"}],"version-history":[{"count":1,"href":"https:\/\/gaviki.com\/blog\/wp-json\/wp\/v2\/posts\/36381\/revisions"}],"predecessor-version":[{"id":36382,"href":"https:\/\/gaviki.com\/blog\/wp-json\/wp\/v2\/posts\/36381\/revisions\/36382"}],"wp:attachment":[{"href":"https:\/\/gaviki.com\/blog\/wp-json\/wp\/v2\/media?parent=36381"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/gaviki.com\/blog\/wp-json\/wp\/v2\/categories?post=36381"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/gaviki.com\/blog\/wp-json\/wp\/v2\/tags?post=36381"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}