{"id":6858,"date":"2014-03-27T17:24:02","date_gmt":"2014-03-27T17:24:02","guid":{"rendered":"https:\/\/schooltutoring.com\/help\/?p=6858"},"modified":"2014-12-02T08:25:31","modified_gmt":"2014-12-02T08:25:31","slug":"determining-oxidation-numbers","status":"publish","type":"post","link":"https:\/\/schooltutoring.com\/help\/determining-oxidation-numbers\/","title":{"rendered":"Determining Oxidation Numbers"},"content":{"rendered":"<h3><b>Overview:<\/b><\/h3>\n<p>Balancing REDOX reactions can be more difficult than balancing any normal equation; however, there are steps that you can take to ensure that you do it correctly and end up with the correct answer.<\/p>\n<p>The first thing you need to know in order to balance REDOX reactions is elements Oxidation Numbers. To make things easier, there are elements that have simple rules to determine their oxidation numbers:<\/p>\n<p>Group 1 metals \u2013 Always +1<\/p>\n<p>Group 2 metals \u2013 Always +2<\/p>\n<p>Oxygen \u2013 typically -2 (see exceptions below)<\/p>\n<p>Hydrogen \u2013 mostly +1 (see the one exception below)<\/p>\n<p>Halogens \u2013 Almost always -1<\/p>\n<p>The sum of all oxidation numbers in a compound must equal the total charge of that compound.<\/p>\n<h3><b>Oxygen Exceptions<\/b><\/h3>\n<p>If the oxygen is in peroxide such as H<sub>2<\/sub>O<sub>2<\/sub>, each oxygen will have an oxidation state of -1 instead of -2.\u00a0 If Oxygen is in the compound is in F<sub>2<\/sub>O it will have an oxygen state of +1.<\/p>\n<h3><b>Hydrogen Exceptions<\/b><\/h3>\n<p>The only hydrogen exception is when you find the hydrogen in a hydride such as NaH, LiH etc. In these cases, hydrogen will have an oxidation state of -1.<\/p>\n<h3><b>Solving for Unknown Oxidation Numbers<\/b><\/h3>\n<p>Now, we have to determine the oxidation states of other elements in a compound. To do this, we simply determine oxidation numbers of other elements in the compound that we already know (based on the rules provided above) and then use these numbers to determine the oxidation number of the element we are looking at. \u00a0Please note that the charge of a compound is always equal to the sum of all oxidation numbers.<\/p>\n<p>Let\u2019s take a look at the following examples:<\/p>\n<p>Mn<sup>2+<\/sup>\u00a0&#8211; Manganese is not on our list of rules. However, we know what the oxidation number is based on the charge. Remember it is always the same as the charge of the compound or ion. Therefore, the oxidation number for Manganese in Mn<sup>2+<\/sup>\u00a0is +2.<\/p>\n<p>O<sub>2<\/sub>\u00a0\u2013 You may jump to conclusions and say that each oxygen has an oxidation number of -2. Note that the charge on oxygen is zero. This indicates that the sum of the oxidation numbers for each oxygen molecule must equal zero. As such, each Oxygen will have an oxidation state of zero.<\/p>\n<p>KMnO<sub>4<\/sub>\u00a0\u2013 These polyatomic compounds may seem very difficult, but with any chemistry question, let\u2019s break it down. Potassium (K) is in the first group in the periodic table. Our rule for group one elements is that they always have an oxidation state of +1. Therefore, K has an oxidation state of +1. For Oxygen, since it is not in peroxide, so each oxygen has a state of -2. Now let\u2019s solve for Mn. To do so set up the following equation:<\/p>\n<p>1K + 1Mn + 4O = 0. Remember the sum of the oxidation states must equal the total charge.<\/p>\n<p>(+1) + 1Mn + (4*-2) = 0<\/p>\n<p>1 + Mn \u2013 8 = 0<\/p>\n<p>Mn \u2013 7 = 0<\/p>\n<p>Mn = 7<\/p>\n<p>Solving this equation, we get an oxidation charge of +7 for Mn.<\/p>\n<p>Following the rules listed here will provide you with a simple method to follow when determining the oxidation numbers of individual elements.<\/p>\n<p><span style=\"color: #ff6600;\"><strong>SchoolTutoring Academy<\/strong><\/span>\u00a0is the premier educational services company for K-12 and college students. We offer tutoring programs for students in K-12, AP classes, and college. To learn more about how we help parents and students in Austin, TX: visit\u00a0<a href=\"https:\/\/schooltutoring.com\/texas-tutors-available\/\">Tutoring in Austin, TX<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"<p>Overview: Balancing REDOX reactions can be more difficult than balancing any normal equation; however, there are steps that you can take to ensure that you do it correctly and end up with the correct answer. The first thing you need to know in order to balance REDOX reactions is elements Oxidation Numbers. To make things [&hellip;]<\/p>\n","protected":false},"author":17,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"inline_featured_image":false,"footnotes":""},"categories":[5,16],"tags":[],"class_list":["post-6858","post","type-post","status-publish","format-standard","hentry","category-chemistry","category-science"],"acf":[],"aioseo_notices":[],"_links":{"self":[{"href":"https:\/\/schooltutoring.com\/help\/wp-json\/wp\/v2\/posts\/6858","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/schooltutoring.com\/help\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/schooltutoring.com\/help\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/schooltutoring.com\/help\/wp-json\/wp\/v2\/users\/17"}],"replies":[{"embeddable":true,"href":"https:\/\/schooltutoring.com\/help\/wp-json\/wp\/v2\/comments?post=6858"}],"version-history":[{"count":0,"href":"https:\/\/schooltutoring.com\/help\/wp-json\/wp\/v2\/posts\/6858\/revisions"}],"wp:attachment":[{"href":"https:\/\/schooltutoring.com\/help\/wp-json\/wp\/v2\/media?parent=6858"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/schooltutoring.com\/help\/wp-json\/wp\/v2\/categories?post=6858"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/schooltutoring.com\/help\/wp-json\/wp\/v2\/tags?post=6858"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}