{"id":1399,"date":"2014-08-12T03:13:03","date_gmt":"2014-08-12T03:13:03","guid":{"rendered":"https:\/\/courses.candelalearning.com\/cheminter\/?post_type=chapter&#038;p=1399"},"modified":"2017-08-31T17:47:41","modified_gmt":"2017-08-31T17:47:41","slug":"kinetics","status":"publish","type":"chapter","link":"https:\/\/courses.lumenlearning.com\/umes-cheminter\/chapter\/kinetics\/","title":{"raw":"Chemical Reaction Rate","rendered":"Chemical Reaction Rate"},"content":{"raw":"<div class=\"textbox learning-objectives\">\r\n<h3>Learning Objectives<\/h3>\r\n<ul id=\"x-ck12-ZjJkZDJmNjVmNmNhMWViMzNiMzAyNDJiYzg4MTNkNjk.-z04\">\r\n \t<li>Define reaction rate.<\/li>\r\n \t<li>Calculate reaction rate when given time and change in concentration.<\/li>\r\n<\/ul>\r\n<\/div>\r\n<div class=\"textbox examples\">\r\n<h3>Two for the price of one!<\/h3>\r\n[caption id=\"\" align=\"aligncenter\" width=\"400\"]<img src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/53\/2014\/08\/19212811\/20140811155712998006.jpeg\" alt=\"Both acceleration and final speed are important in determining overall velocity\" width=\"400\" height=\"375\" \/> Drag Racing. Image from Christopher Ziemnowicz (<a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:1972_AMC_Gremlin_veteran_dragster_99_WIBG_mdD-ls.jpg\">Wikimedia<\/a>: CZmarlin).[\/caption]\r\n<p id=\"x-ck12-NzZlZmEyYWY2MWFlNjg0ZWM4NGE3NGJiODc2MWU1NmI.-upt\">Drag racing is a sport where two cars start from a dead stop and drive as fast as they can down a quarter-mile strip. At the end of the strip are timers that determine both elapsed time (how long did it take for them to cover the quarter mile) and top speed (how fast were they going as they went through the timer chute). Both pieces of data are important. One car may accelerate faster and get ahead that way, while the other care may be slower off the line, but can get up to a higher top speed at the end of the run.<\/p>\r\n\r\n<\/div>\r\n<h2>Chemical Reaction Rate<\/h2>\r\n<p id=\"x-ck12-YmI0MDg1YTM4NThkY2ZkOWZiYjlkYzQ0NGRhNzc0M2E.-tww\">Chemical reactions vary widely in the speeds with which they occur. Some reactions occur very quickly. If a lighted match is brought in contact with lighter fluid or another flammable liquid, it erupts into flame instantly and burns fast. Other reactions occur very slowly. A container of milk in the refrigerator will be good to drink for weeks before it begins to turn sour. Millions of years were required for dead plants under Earth\u2019s surface to accumulate and eventually turn into fossil fuels such as coal and oil.<\/p>\r\n<p id=\"x-ck12-ZjI0NmQ2MmNmMWQyMGFhZTNlOGFjMmRkYjEzYjBiMTU.-1fi\">Chemists need to be concerned with the rates at which chemical reactions occur. Rate is another word for speed. If a sprinter takes 11.0 s to run a 100 m dash, his rate or speed is given by the distance traveled divided by the time.<\/p>\r\n<p id=\"x-ck12-jwg\"><img id=\"x-ck12-MTM2NzIxOTg5MjQzMw..\" class=\"x-ck12-block-math aligncenter\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/53\/2014\/08\/19212812\/3774e4556bfb04ac0e5908ec5bb23499.png\" alt=\"text{speed}=frac{text{distance}}{text{time}}=frac{100 text{ m}}{11.0 text{ s}}=9.09 text{ m\/s}\" width=\"303\" height=\"39\" \/><\/p>\r\n<p id=\"x-ck12-MTYyYWIyNmRhN2NlMjU3OTZlOGQxYjU2NzlmN2MzYTE.-3vw\">The sprinter\u2019s average running rate for the race is 9.09 m\/s. We say that it is his average rate because he did not run at that speed for the entire race. At the very beginning of the race, while coming from a standstill, his rate must be slower until he is able to get up to his top speed. His top speed must then be greater than 9.09 m\/s so that taken over the entire race, the average ends up at 9.09 m\/s.<\/p>\r\n\r\n<div id=\"x-ck12-M2ZiMTNhMDgzZTM5ZmU1NWQzMWQ4NjAxZTY1OGNkODA.-3ki\" class=\"x-ck12-img-thumbnail x-ck12-nofloat\">\r\n\r\n[caption id=\"\" align=\"aligncenter\" width=\"140\"]<img id=\"x-ck12-OTgwNDUtMTM2NzIxOTczMS04OC03LXN0b2NrLXBob3RvLWJlcmxpbi1hdWd1c3QtYXNpYW4tYm9sdC1vZi1qYW1hamNhLWluLXRoZS10aC1pYWFmLXdvcmxkLWNoYW1waW9uc2hpcHMtaW4tYXRobGV0aWNzLWF1Z3VzdC0zNjA2NjgxNw..\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/53\/2014\/08\/19212813\/20140811155713145174.jpeg\" alt=\"Runner on a track. Rate is the change of a quantity over time.\" width=\"140\" height=\"192\" longdesc=\"Runner.\" \/> Figure 1. Usain Bolt. From\u00a0<a href=\"https:\/\/www.flickr.com\/photos\/hkedwardtong\/3528266605\/\">Flickr:hkedwardtong<\/a>.[\/caption]\r\n\r\n<\/div>\r\n<p id=\"x-ck12-ZTY3MjUxYzU5ZGU0ODM0M2RmNTZiOGZhMGQ2MWNkM2M.-kbl\">Chemical reactions can\u2019t be measured in units of meters per second, as that would not make any sense. A <strong> reaction rate <\/strong> is the change in concentration of a reactant or product with time. Suppose that a simple reaction were to take place in which a 1.00 M aqueous solution of substance\u00a0 <img class=\"x-ck12-math\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/53\/2014\/08\/19211811\/d5ebd507fac84fdb3364e6593d198a76.png\" alt=\"A\" width=\"13\" height=\"12\" \/> was converted to substance <img class=\"x-ck12-math\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/53\/2014\/08\/19211811\/00025e2ee78e7b712fbb42f74f2d6cb7.png\" alt=\"B\" width=\"14\" height=\"12\" \/> .<\/p>\r\n<p id=\"x-ck12-6dg\"><img class=\"x-ck12-block-math aligncenter\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/53\/2014\/08\/19212814\/9b0c47e7ad080adbf54d71c3414722e6.png\" alt=\"A(aq) rightarrow B(aq)\" width=\"131\" height=\"18\" \/><\/p>\r\n<p id=\"x-ck12-Nzk3M2UzYzEyNDhmZGZjOTM2Yzc4NDU1ZmYwZjY3MjU.-h6f\">Suppose that after 20.0 seconds, the concentration of\u00a0 <img id=\"x-ck12-MTM2NzIxOTg5MjQzNA..\" class=\"x-ck12-math\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/53\/2014\/08\/19211811\/d5ebd507fac84fdb3364e6593d198a76.png\" alt=\"A\" width=\"13\" height=\"12\" \/> had dropped from 1.00 M to 0.72 M as\u00a0 <img class=\"x-ck12-math\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/53\/2014\/08\/19211811\/d5ebd507fac84fdb3364e6593d198a76.png\" alt=\"A\" width=\"13\" height=\"12\" \/> was slowly being converted to <img id=\"x-ck12-MTM2NzIxOTg5MjQzNQ..\" class=\"x-ck12-math\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/53\/2014\/08\/19211811\/00025e2ee78e7b712fbb42f74f2d6cb7.png\" alt=\"B\" width=\"14\" height=\"12\" \/> . We can express the rate of this reaction as the change in concentration of\u00a0 <img class=\"x-ck12-math\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/53\/2014\/08\/19211811\/d5ebd507fac84fdb3364e6593d198a76.png\" alt=\"A\" width=\"13\" height=\"12\" \/> divided by the time.<\/p>\r\n<p id=\"x-ck12-vzb\"><img id=\"x-ck12-MTM2NzIxOTg5MjQzNg..\" class=\"x-ck12-block-math aligncenter\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/53\/2014\/08\/19212815\/c55739c2011f2b96223318802bf68797.png\" alt=\"text{rate}=-frac{Delta [A]}{Delta t}=-frac{[A]_{text{final}}-[A]_{text{initial}}}{Delta t}\" width=\"280\" height=\"38\" \/><\/p>\r\n<p id=\"x-ck12-Y2EwZmIwMTcwYzQzZThhYzNlOTI5NjdmOTBmMjdlZTM.-bsp\">A bracket around a symbol or formula means the concentration in molarity of that substance. The change in concentration of\u00a0 <img class=\"x-ck12-math\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/53\/2014\/08\/19211811\/d5ebd507fac84fdb3364e6593d198a76.png\" alt=\"A\" width=\"13\" height=\"12\" \/> is its final concentration minus its initial concentration. Because the concentration of\u00a0 <img class=\"x-ck12-math\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/53\/2014\/08\/19211811\/d5ebd507fac84fdb3364e6593d198a76.png\" alt=\"A\" width=\"13\" height=\"12\" \/> is decreasing over time, the negative sign is used. Thus, the rate for the reaction is positive and the units are molarity per second or M\/s.<\/p>\r\n<p id=\"x-ck12-s7a\"><img class=\"x-ck12-block-math aligncenter\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/53\/2014\/08\/19212816\/d2cd9014d8615a5f7bf2cf74cdeca8d3.png\" alt=\"text{rate}=-frac{0.72 text{ M}-1.00 text{ M}}{20.0 text{ s}}=-frac{-0.28 text{ M}}{20.0 text{ s}}=0.014 text{ M\/s}\" width=\"416\" height=\"38\" \/><\/p>\r\n<p id=\"x-ck12-MGI2YWI5ODRiMTZkZDA1NzUxNmE2Y2RjNWYyYjMyYjQ.-tyv\">The molarity of\u00a0 <img class=\"x-ck12-math\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/53\/2014\/08\/19211811\/d5ebd507fac84fdb3364e6593d198a76.png\" alt=\"A\" width=\"13\" height=\"12\" \/> decreases by an average rate of 0.014 M every second. In summary, the rate of a chemical reaction is measured by the change in concentration over time for a reactant or product. The unit of measurement for a reaction rate is molarity per second (M\/s).<\/p>\r\n\r\n<div class=\"textbox key-takeaways\">\r\n<h3>Summary<\/h3>\r\n<ul id=\"x-ck12-YzIyZjE2ZTUwYjA2ZDgwYzlhZWExMjhhMGM2YmJlZmQ.-vot\">\r\n \t<li>The reaction rate indicates how fast the reaction proceeds.<\/li>\r\n<\/ul>\r\n<\/div>\r\n<div class=\"textbox exercises\">\r\n<h3>Practice<\/h3>\r\n<p id=\"x-ck12-ZDA1NTE4MmE3ZWNhMTc1ZjZmZjlhNTc2YTQzZWI5ZTg.-lfj\">Read <a href=\"https:\/\/chem.libretexts.org\/Core\/Physical_and_Theoretical_Chemistry\/Kinetics\/Reaction_Rates\/Reaction_Rate\/The_Rate_of_a_Chemical_Reaction\" target=\"_blank\" rel=\"noopener\">this page on The Rate of a Chemical Reaction<\/a> and answer the following questions:<\/p>\r\n\r\n<ol id=\"x-ck12-Y2JlODg3Y2Y5OTdmZDkyZThkZTMyZWYyMjdlNTUzODc.-veg\">\r\n \t<li>Why is the rate of disappearance a negative value?<\/li>\r\n \t<li>What is the average rate of reaction?<\/li>\r\n \t<li>What is the instantaneous rate of reaction?<\/li>\r\n<\/ol>\r\n<\/div>\r\n<div class=\"textbox exercises\">\r\n<h3>Review<\/h3>\r\n<ol id=\"x-ck12-MGU2MjQ2NjUwZTNkMjNmMzQ4ZTIzNTY5Y2Q3OWIxOWU.-tld\">\r\n \t<li>What is another word for rate?<\/li>\r\n \t<li>What does [ ] stand for?<\/li>\r\n \t<li>What are the units of reaction rate?<\/li>\r\n<\/ol>\r\n<\/div>\r\n<h2 class=\"x-ck12-data-problem-set\">Glossary<\/h2>\r\n<div class=\"x-ck12-data-vocabulary\">\r\n<ul id=\"x-ck12-ZGJlZGY4NmNmMjRiNjRiYTBlNzM4ZmJiMWRhZDhlZjE.-rne\">\r\n \t<li><strong> reaction rate: <\/strong> The change in concentration of a reactant or product with time.<\/li>\r\n<\/ul>\r\n<\/div>","rendered":"<div class=\"textbox learning-objectives\">\n<h3>Learning Objectives<\/h3>\n<ul id=\"x-ck12-ZjJkZDJmNjVmNmNhMWViMzNiMzAyNDJiYzg4MTNkNjk.-z04\">\n<li>Define reaction rate.<\/li>\n<li>Calculate reaction rate when given time and change in concentration.<\/li>\n<\/ul>\n<\/div>\n<div class=\"textbox examples\">\n<h3>Two for the price of one!<\/h3>\n<div style=\"width: 410px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/53\/2014\/08\/19212811\/20140811155712998006.jpeg\" alt=\"Both acceleration and final speed are important in determining overall velocity\" width=\"400\" height=\"375\" \/><\/p>\n<p class=\"wp-caption-text\">Drag Racing. Image from Christopher Ziemnowicz (<a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:1972_AMC_Gremlin_veteran_dragster_99_WIBG_mdD-ls.jpg\">Wikimedia<\/a>: CZmarlin).<\/p>\n<\/div>\n<p id=\"x-ck12-NzZlZmEyYWY2MWFlNjg0ZWM4NGE3NGJiODc2MWU1NmI.-upt\">Drag racing is a sport where two cars start from a dead stop and drive as fast as they can down a quarter-mile strip. At the end of the strip are timers that determine both elapsed time (how long did it take for them to cover the quarter mile) and top speed (how fast were they going as they went through the timer chute). Both pieces of data are important. One car may accelerate faster and get ahead that way, while the other care may be slower off the line, but can get up to a higher top speed at the end of the run.<\/p>\n<\/div>\n<h2>Chemical Reaction Rate<\/h2>\n<p id=\"x-ck12-YmI0MDg1YTM4NThkY2ZkOWZiYjlkYzQ0NGRhNzc0M2E.-tww\">Chemical reactions vary widely in the speeds with which they occur. Some reactions occur very quickly. If a lighted match is brought in contact with lighter fluid or another flammable liquid, it erupts into flame instantly and burns fast. Other reactions occur very slowly. A container of milk in the refrigerator will be good to drink for weeks before it begins to turn sour. Millions of years were required for dead plants under Earth\u2019s surface to accumulate and eventually turn into fossil fuels such as coal and oil.<\/p>\n<p id=\"x-ck12-ZjI0NmQ2MmNmMWQyMGFhZTNlOGFjMmRkYjEzYjBiMTU.-1fi\">Chemists need to be concerned with the rates at which chemical reactions occur. Rate is another word for speed. If a sprinter takes 11.0 s to run a 100 m dash, his rate or speed is given by the distance traveled divided by the time.<\/p>\n<p id=\"x-ck12-jwg\"><img loading=\"lazy\" decoding=\"async\" id=\"x-ck12-MTM2NzIxOTg5MjQzMw..\" class=\"x-ck12-block-math aligncenter\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/53\/2014\/08\/19212812\/3774e4556bfb04ac0e5908ec5bb23499.png\" alt=\"text{speed}=frac{text{distance}}{text{time}}=frac{100 text{ m}}{11.0 text{ s}}=9.09 text{ m\/s}\" width=\"303\" height=\"39\" \/><\/p>\n<p id=\"x-ck12-MTYyYWIyNmRhN2NlMjU3OTZlOGQxYjU2NzlmN2MzYTE.-3vw\">The sprinter\u2019s average running rate for the race is 9.09 m\/s. We say that it is his average rate because he did not run at that speed for the entire race. At the very beginning of the race, while coming from a standstill, his rate must be slower until he is able to get up to his top speed. His top speed must then be greater than 9.09 m\/s so that taken over the entire race, the average ends up at 9.09 m\/s.<\/p>\n<div id=\"x-ck12-M2ZiMTNhMDgzZTM5ZmU1NWQzMWQ4NjAxZTY1OGNkODA.-3ki\" class=\"x-ck12-img-thumbnail x-ck12-nofloat\">\n<div style=\"width: 150px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" id=\"x-ck12-OTgwNDUtMTM2NzIxOTczMS04OC03LXN0b2NrLXBob3RvLWJlcmxpbi1hdWd1c3QtYXNpYW4tYm9sdC1vZi1qYW1hamNhLWluLXRoZS10aC1pYWFmLXdvcmxkLWNoYW1waW9uc2hpcHMtaW4tYXRobGV0aWNzLWF1Z3VzdC0zNjA2NjgxNw..\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/53\/2014\/08\/19212813\/20140811155713145174.jpeg\" alt=\"Runner on a track. Rate is the change of a quantity over time.\" width=\"140\" height=\"192\" longdesc=\"Runner.\" \/><\/p>\n<p class=\"wp-caption-text\">Figure 1. Usain Bolt. From\u00a0<a href=\"https:\/\/www.flickr.com\/photos\/hkedwardtong\/3528266605\/\">Flickr:hkedwardtong<\/a>.<\/p>\n<\/div>\n<\/div>\n<p id=\"x-ck12-ZTY3MjUxYzU5ZGU0ODM0M2RmNTZiOGZhMGQ2MWNkM2M.-kbl\">Chemical reactions can\u2019t be measured in units of meters per second, as that would not make any sense. A <strong> reaction rate <\/strong> is the change in concentration of a reactant or product with time. Suppose that a simple reaction were to take place in which a 1.00 M aqueous solution of substance\u00a0 <img loading=\"lazy\" decoding=\"async\" class=\"x-ck12-math\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/53\/2014\/08\/19211811\/d5ebd507fac84fdb3364e6593d198a76.png\" alt=\"A\" width=\"13\" height=\"12\" \/> was converted to substance <img loading=\"lazy\" decoding=\"async\" class=\"x-ck12-math\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/53\/2014\/08\/19211811\/00025e2ee78e7b712fbb42f74f2d6cb7.png\" alt=\"B\" width=\"14\" height=\"12\" \/> .<\/p>\n<p id=\"x-ck12-6dg\"><img loading=\"lazy\" decoding=\"async\" class=\"x-ck12-block-math aligncenter\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/53\/2014\/08\/19212814\/9b0c47e7ad080adbf54d71c3414722e6.png\" alt=\"A(aq) rightarrow B(aq)\" width=\"131\" height=\"18\" \/><\/p>\n<p id=\"x-ck12-Nzk3M2UzYzEyNDhmZGZjOTM2Yzc4NDU1ZmYwZjY3MjU.-h6f\">Suppose that after 20.0 seconds, the concentration of\u00a0 <img loading=\"lazy\" decoding=\"async\" id=\"x-ck12-MTM2NzIxOTg5MjQzNA..\" class=\"x-ck12-math\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/53\/2014\/08\/19211811\/d5ebd507fac84fdb3364e6593d198a76.png\" alt=\"A\" width=\"13\" height=\"12\" \/> had dropped from 1.00 M to 0.72 M as\u00a0 <img loading=\"lazy\" decoding=\"async\" class=\"x-ck12-math\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/53\/2014\/08\/19211811\/d5ebd507fac84fdb3364e6593d198a76.png\" alt=\"A\" width=\"13\" height=\"12\" \/> was slowly being converted to <img loading=\"lazy\" decoding=\"async\" id=\"x-ck12-MTM2NzIxOTg5MjQzNQ..\" class=\"x-ck12-math\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/53\/2014\/08\/19211811\/00025e2ee78e7b712fbb42f74f2d6cb7.png\" alt=\"B\" width=\"14\" height=\"12\" \/> . We can express the rate of this reaction as the change in concentration of\u00a0 <img loading=\"lazy\" decoding=\"async\" class=\"x-ck12-math\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/53\/2014\/08\/19211811\/d5ebd507fac84fdb3364e6593d198a76.png\" alt=\"A\" width=\"13\" height=\"12\" \/> divided by the time.<\/p>\n<p id=\"x-ck12-vzb\"><img loading=\"lazy\" decoding=\"async\" id=\"x-ck12-MTM2NzIxOTg5MjQzNg..\" class=\"x-ck12-block-math aligncenter\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/53\/2014\/08\/19212815\/c55739c2011f2b96223318802bf68797.png\" alt=\"text{rate}=-frac{Delta [A]}{Delta t}=-frac{[A]_{text{final}}-[A]_{text{initial}}}{Delta t}\" width=\"280\" height=\"38\" \/><\/p>\n<p id=\"x-ck12-Y2EwZmIwMTcwYzQzZThhYzNlOTI5NjdmOTBmMjdlZTM.-bsp\">A bracket around a symbol or formula means the concentration in molarity of that substance. The change in concentration of\u00a0 <img loading=\"lazy\" decoding=\"async\" class=\"x-ck12-math\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/53\/2014\/08\/19211811\/d5ebd507fac84fdb3364e6593d198a76.png\" alt=\"A\" width=\"13\" height=\"12\" \/> is its final concentration minus its initial concentration. Because the concentration of\u00a0 <img loading=\"lazy\" decoding=\"async\" class=\"x-ck12-math\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/53\/2014\/08\/19211811\/d5ebd507fac84fdb3364e6593d198a76.png\" alt=\"A\" width=\"13\" height=\"12\" \/> is decreasing over time, the negative sign is used. Thus, the rate for the reaction is positive and the units are molarity per second or M\/s.<\/p>\n<p id=\"x-ck12-s7a\"><img loading=\"lazy\" decoding=\"async\" class=\"x-ck12-block-math aligncenter\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/53\/2014\/08\/19212816\/d2cd9014d8615a5f7bf2cf74cdeca8d3.png\" alt=\"text{rate}=-frac{0.72 text{ M}-1.00 text{ M}}{20.0 text{ s}}=-frac{-0.28 text{ M}}{20.0 text{ s}}=0.014 text{ M\/s}\" width=\"416\" height=\"38\" \/><\/p>\n<p id=\"x-ck12-MGI2YWI5ODRiMTZkZDA1NzUxNmE2Y2RjNWYyYjMyYjQ.-tyv\">The molarity of\u00a0 <img loading=\"lazy\" decoding=\"async\" class=\"x-ck12-math\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/53\/2014\/08\/19211811\/d5ebd507fac84fdb3364e6593d198a76.png\" alt=\"A\" width=\"13\" height=\"12\" \/> decreases by an average rate of 0.014 M every second. In summary, the rate of a chemical reaction is measured by the change in concentration over time for a reactant or product. The unit of measurement for a reaction rate is molarity per second (M\/s).<\/p>\n<div class=\"textbox key-takeaways\">\n<h3>Summary<\/h3>\n<ul id=\"x-ck12-YzIyZjE2ZTUwYjA2ZDgwYzlhZWExMjhhMGM2YmJlZmQ.-vot\">\n<li>The reaction rate indicates how fast the reaction proceeds.<\/li>\n<\/ul>\n<\/div>\n<div class=\"textbox exercises\">\n<h3>Practice<\/h3>\n<p id=\"x-ck12-ZDA1NTE4MmE3ZWNhMTc1ZjZmZjlhNTc2YTQzZWI5ZTg.-lfj\">Read <a href=\"https:\/\/chem.libretexts.org\/Core\/Physical_and_Theoretical_Chemistry\/Kinetics\/Reaction_Rates\/Reaction_Rate\/The_Rate_of_a_Chemical_Reaction\" target=\"_blank\" rel=\"noopener\">this page on The Rate of a Chemical Reaction<\/a> and answer the following questions:<\/p>\n<ol id=\"x-ck12-Y2JlODg3Y2Y5OTdmZDkyZThkZTMyZWYyMjdlNTUzODc.-veg\">\n<li>Why is the rate of disappearance a negative value?<\/li>\n<li>What is the average rate of reaction?<\/li>\n<li>What is the instantaneous rate of reaction?<\/li>\n<\/ol>\n<\/div>\n<div class=\"textbox exercises\">\n<h3>Review<\/h3>\n<ol id=\"x-ck12-MGU2MjQ2NjUwZTNkMjNmMzQ4ZTIzNTY5Y2Q3OWIxOWU.-tld\">\n<li>What is another word for rate?<\/li>\n<li>What does [ ] stand for?<\/li>\n<li>What are the units of reaction rate?<\/li>\n<\/ol>\n<\/div>\n<h2 class=\"x-ck12-data-problem-set\">Glossary<\/h2>\n<div class=\"x-ck12-data-vocabulary\">\n<ul id=\"x-ck12-ZGJlZGY4NmNmMjRiNjRiYTBlNzM4ZmJiMWRhZDhlZjE.-rne\">\n<li><strong> reaction rate: <\/strong> The change in concentration of a reactant or product with time.<\/li>\n<\/ul>\n<\/div>\n\n\t\t\t <section class=\"citations-section\" role=\"contentinfo\">\n\t\t\t <h3>Candela Citations<\/h3>\n\t\t\t\t\t <div>\n\t\t\t\t\t\t <div id=\"citation-list-1399\">\n\t\t\t\t\t\t\t <div class=\"licensing\"><div class=\"license-attribution-dropdown-subheading\">CC licensed content, Shared previously<\/div><ul class=\"citation-list\"><li>Chemistry Concepts Intermediate. <strong>Authored by<\/strong>: Calbreath, Baxter, et al.. <strong>Provided by<\/strong>: CK12.org. <strong>Located at<\/strong>: <a target=\"_blank\" href=\"http:\/\/www.ck12.org\/book\/CK-12-Chemistry-Concepts-Intermediate\/\">http:\/\/www.ck12.org\/book\/CK-12-Chemistry-Concepts-Intermediate\/<\/a>. <strong>License<\/strong>: <em><a target=\"_blank\" rel=\"license\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\">CC BY-NC: Attribution-NonCommercial<\/a><\/em><\/li><\/ul><\/div>\n\t\t\t\t\t\t <\/div>\n\t\t\t\t\t <\/div>\n\t\t\t <\/section>","protected":false},"author":1507,"menu_order":1,"template":"","meta":{"_candela_citation":"[{\"type\":\"cc\",\"description\":\"Chemistry Concepts Intermediate\",\"author\":\"Calbreath, Baxter, et al.\",\"organization\":\"CK12.org\",\"url\":\"http:\/\/www.ck12.org\/book\/CK-12-Chemistry-Concepts-Intermediate\/\",\"project\":\"\",\"license\":\"cc-by-nc\",\"license_terms\":\"\"}]","CANDELA_OUTCOMES_GUID":"","pb_show_title":"on","pb_short_title":"","pb_subtitle":"","pb_authors":[],"pb_section_license":""},"chapter-type":[],"contributor":[],"license":[],"class_list":["post-1399","chapter","type-chapter","status-publish","hentry"],"part":2339,"_links":{"self":[{"href":"https:\/\/courses.lumenlearning.com\/umes-cheminter\/wp-json\/pressbooks\/v2\/chapters\/1399","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/courses.lumenlearning.com\/umes-cheminter\/wp-json\/pressbooks\/v2\/chapters"}],"about":[{"href":"https:\/\/courses.lumenlearning.com\/umes-cheminter\/wp-json\/wp\/v2\/types\/chapter"}],"author":[{"embeddable":true,"href":"https:\/\/courses.lumenlearning.com\/umes-cheminter\/wp-json\/wp\/v2\/users\/1507"}],"version-history":[{"count":8,"href":"https:\/\/courses.lumenlearning.com\/umes-cheminter\/wp-json\/pressbooks\/v2\/chapters\/1399\/revisions"}],"predecessor-version":[{"id":3682,"href":"https:\/\/courses.lumenlearning.com\/umes-cheminter\/wp-json\/pressbooks\/v2\/chapters\/1399\/revisions\/3682"}],"part":[{"href":"https:\/\/courses.lumenlearning.com\/umes-cheminter\/wp-json\/pressbooks\/v2\/parts\/2339"}],"metadata":[{"href":"https:\/\/courses.lumenlearning.com\/umes-cheminter\/wp-json\/pressbooks\/v2\/chapters\/1399\/metadata\/"}],"wp:attachment":[{"href":"https:\/\/courses.lumenlearning.com\/umes-cheminter\/wp-json\/wp\/v2\/media?parent=1399"}],"wp:term":[{"taxonomy":"chapter-type","embeddable":true,"href":"https:\/\/courses.lumenlearning.com\/umes-cheminter\/wp-json\/pressbooks\/v2\/chapter-type?post=1399"},{"taxonomy":"contributor","embeddable":true,"href":"https:\/\/courses.lumenlearning.com\/umes-cheminter\/wp-json\/wp\/v2\/contributor?post=1399"},{"taxonomy":"license","embeddable":true,"href":"https:\/\/courses.lumenlearning.com\/umes-cheminter\/wp-json\/wp\/v2\/license?post=1399"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}