{"id":33,"date":"2015-07-09T16:51:29","date_gmt":"2015-07-09T16:51:29","guid":{"rendered":"https:\/\/courses.candelalearning.com\/biolabsxmaster\/?post_type=chapter&#038;p=33"},"modified":"2020-08-31T20:18:21","modified_gmt":"2020-08-31T20:18:21","slug":"the-chemistry-of-life","status":"publish","type":"chapter","link":"https:\/\/courses.lumenlearning.com\/biolabs1\/chapter\/the-chemistry-of-life\/","title":{"raw":"The Chemistry of Life","rendered":"The Chemistry of Life"},"content":{"raw":"<div>\r\n\r\nAll life exists within the context of its environment. Each environment is characterized by its biological,\u00a0physical, and chemical properties. Since organisms are adapted to a specific environment, radical changes in\u00a0these conditions often result in injury to the individual or possibly extinction of the species. Recent reports of\u00a0declining frog populations, for example, have been correlated with increased ultraviolet radiation from the sun\u00a0(specifically UVB). Chemical reactions that take place inside of an organism are dependent upon both internal\u00a0and external chemical and physical properties. We will explore some of these properties in today's lab.\r\n<h2>Part 1: pH Chemistry<\/h2>\r\nAlthough water is generally regarded as a stable compound, individual water molecules are constantly gaining,\u00a0losing, and swapping hydrogen atoms. This process is represented by the following chemical reaction:\r\n<p style=\"text-align: center;\">H<sub>2<\/sub>O\u00a0\u2194\u00a0OH\u00a0+\u00a0H<\/p>\r\nPure water with a pH of 7 has equal numbers of hydrogen and hydroxide\u00a0ions at any given moment. Water is considered to be a neutral substance.\u00a0The pH of any solution can be determined by calculating the total\u00a0concentration of hydrogen ions in the solution.\r\n\r\n<\/div>\r\n<div class=\"textbox shaded\">\r\n<h3><strong>What is a MOLE?<\/strong><\/h3>\r\nA mole is a term used to describe\u00a0the quantity of something. If you\u00a0have a mole of paperclips, that\u00a0means you have paperclips. This\u00a0is similar to the way we use the word \"dozen.\" We know that if\u00a0you have a dozen paperclips, it\u00a0means you have 12 of them.\r\n\r\n<strong>1 dozen = 12 <\/strong>\r\n\r\n<strong>1 mole = 6.02\u00d710<sub>23<\/sub><\/strong>\r\n\r\n<\/div>\r\n<div>\r\n\r\nScientists measure acidity using the pH scale. The pH scale ranges from 0 to 14, and the numbers represent the concentration of hydrogen ions<sub>\u20131<\/sub>\u00a0in the substance. For example, battery acid, with a pH of 1, has 1\u00d710\u00a0moles of hydrogen ions per liter of solution. Ammonia, which is a very\u00a0basic substance with a pH of 12, has 1\u00d710<sub>\u201312<\/sub> moles of hydrogen ions per\u00a0liter of solution. The more acidic the solution, the more hydrogen ions it\u00a0contains.\r\n\r\n<\/div>\r\n<div>\r\n\r\nExcessive changes in pH can cause metabolic and ecological problems.\u00a0For example, the pH of your blood is carefully kept between 7.35 and\u00a07.45. Any deviation above or below this range will result in alkalosis or acidosis, and both conditions can be\u00a0deadly. Acid rain, on the other hand, can dissolve toxic metals from the soil particles into the soil solution and\u00a0impair plant growth. As we will soon see, plant health is a factor that quickly affects most other life forms on\u00a0the planet.\r\n\r\n<a href=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/690\/2015\/07\/23014011\/Screen-Shot-2015-07-09-at-10.04.56-AM.png\"><img class=\"aligncenter size-full wp-image-39\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/690\/2015\/07\/23014011\/Screen-Shot-2015-07-09-at-10.04.56-AM.png\" alt=\"Screen Shot 2015-07-09 at 10.04.56 AM\" width=\"884\" height=\"142\" \/><\/a>\r\n\r\n<\/div>\r\n<div>\r\n<h3>Materials<\/h3>\r\n<ul>\r\n \t<li>pH paper (1\u201314)<\/li>\r\n \t<li>Plastic tray with wells<\/li>\r\n \t<li>Wax pencil<\/li>\r\n<\/ul>\r\n<h3>Procedure<\/h3>\r\nFollowing the instructions given by your teacher, measure the pH of each solution using pH paper. \u00a0Record the pH of these items below.\r\n<ul>\r\n \t<li>Tap water<\/li>\r\n \t<li>Distilled water<\/li>\r\n \t<li>Bleach<\/li>\r\n \t<li>Aspirin<\/li>\r\n \t<li>Lemon juice<\/li>\r\n \t<li>Milk<\/li>\r\n<\/ul>\r\n<\/div>\r\n<div>\r\n<h2><strong>Part 2: Buffers <\/strong><\/h2>\r\nBuffers are molecules that resist changes in pH. They can take up and release excess hydrogen ions in a\u00a0solution and therefore prevent drastic changes in pH, regardless of whether acid or base is added to the solution.\u00a0The net result is that the pH of the solution remains relatively stable (until the buffer is overwhelmed). Buffers\u00a0are commonly found in dissolved minerals, soils, and in living organisms.\r\n\r\nFor example, buffers can play a protective role in lake ecosystems. In a lowland lake, acid rain causes very\u00a0little fluctuation in pH because these lakes are typically high in organic molecules that act as buffers. A lake\u00a0with little buffering capacity, such as a high alpine lake low in organic molecules, will experience a much\u00a0greater change in overall pH as a result of acid precipitation.\r\n<h3>Materials<\/h3>\r\n<ul>\r\n \t<li>pH paper (1\u201314)<\/li>\r\n \t<li>Tap water (H<sub>2<\/sub>O)<\/li>\r\n \t<li>2 beakers (250 mL)<\/li>\r\n \t<li>1g NaHCO<sub>3<\/sub> (baking soda)<\/li>\r\n \t<li>0.001 M HCl (hydrochloric acid)<\/li>\r\n \t<li>Wax pencil<\/li>\r\n<\/ul>\r\n<h3>Procedure<\/h3>\r\n<ol>\r\n \t<li>Fill two beakers with 50 ml of tap water. Label one beaker \"buffered\" and label the other beaker\u00a0\"unbuffered.\"<\/li>\r\n \t<li>Add 1 gram of baking soda to the \"buffered\" beaker. Swirl to dissolve.<\/li>\r\n \t<li>Using the pH strips, measure the pH of both beakers. Record all measurements in Table 1.<\/li>\r\n \t<li>Add 10 ml of 0.001 M HCl (hydrochloric acid) to each beaker and swirl.<\/li>\r\n \t<li>Measure the pH of the two beakers and record.<\/li>\r\n \t<li>Repeat steps 3\u20135 until you have added a total of 50 ml of 0.001 M HCl to each beaker.<\/li>\r\n<\/ol>\r\n<h3>Data<\/h3>\r\nRecord the pH of your buffered and unbuffered solutions after each addition of 10 mL of hydrochloric\u00a0acid to each beaker.\r\n<table>\r\n<thead>\r\n<tr>\r\n<th colspan=\"3\"><strong>Table 1. Buffered and Unbuffered Solutions<\/strong><\/th>\r\n<\/tr>\r\n<\/thead>\r\n<tbody>\r\n<tr>\r\n<th rowspan=\"2\">Volume (mL) of\r\n0.001 M HCl<\/th>\r\n<th colspan=\"2\">ph<\/th>\r\n<\/tr>\r\n<tr>\r\n<th>Buffered Solution<\/th>\r\n<th>Unbuffered Solution<\/th>\r\n<\/tr>\r\n<tr>\r\n<td style=\"text-align: center;\">0<\/td>\r\n<td><\/td>\r\n<td><\/td>\r\n<\/tr>\r\n<tr>\r\n<td style=\"text-align: center;\">10<\/td>\r\n<td><\/td>\r\n<td><\/td>\r\n<\/tr>\r\n<tr>\r\n<td style=\"text-align: center;\">20<\/td>\r\n<td><\/td>\r\n<td><\/td>\r\n<\/tr>\r\n<tr>\r\n<td style=\"text-align: center;\">30<\/td>\r\n<td><\/td>\r\n<td><\/td>\r\n<\/tr>\r\n<tr>\r\n<td style=\"text-align: center;\">40<\/td>\r\n<td><\/td>\r\n<td><\/td>\r\n<\/tr>\r\n<tr>\r\n<td style=\"text-align: center;\">50<\/td>\r\n<td><\/td>\r\n<td><\/td>\r\n<\/tr>\r\n<\/tbody>\r\n<\/table>\r\n<\/div>\r\n<h3>Data Analysis<\/h3>\r\n<div>\r\n\r\nIllustrate the buffering capacity of each solution by graphing your results below. Place the volume of \u00a0HCl on the x-axis and the pH value on the y-axis. Don't forget to give your graph a title.\r\n\r\n<img class=\"alignnone wp-image-34 size-full\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/690\/2015\/07\/23014009\/Screen-Shot-2015-07-09-at-9.23.59-AM.png\" alt=\"Screen Shot 2015-07-09 at 9.23.59 AM\" width=\"650\" height=\"265\" \/>\r\n\r\nYou can download this\u00a0<a href=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/690\/2016\/02\/23014129\/GraphPaper.pdf\">graph paper template<\/a>\u00a0to complete this portion.\r\n\r\n<\/div>\r\n<div>\r\n<h2><strong>Part 3: Buffers in the Blood <\/strong><\/h2>\r\nBicarbonate ions act as a powerful buffer in your blood. They are created when carbon dioxide (CO<sub>2<\/sub>), produced\u00a0during cellular respiration, reacts with water:\r\n\r\nCO<sub>2\u00a0<\/sub>+ H<sub>2<\/sub>O \u2194 H<sub>2<\/sub>CO<sub>3<\/sub> \u2194 HCO<sub>3\u2013<\/sub>+\u00a0H+\r\n\r\nNotice that hydrogen ions are also generated, which increases the acidity of blood and decreases the pH. In\u00a0your body, the hydrogen ions are absorbed by hemoglobin molecules on your red blood cells. Meanwhile, the\u00a0bicarbonate ions circulate in the blood plasma, preventing rapid pH changes. As your blood circulates past the\u00a0metabolizing cells, more and more CO<sub>2<\/sub> enters your bloodstream and turns to bicarbonate ions. By the time the\u00a0blood reaches the lungs, it is full of bicarbonate and hydrogen ions. The bicarbonate and hydrogen ions now\u00a0combine and the reaction goes from right to left, releasing the CO<sub>2<\/sub>, which is now breathed out.\u00a0In this exercise, you will bubble CO<sub>2<\/sub> into tap water and demonstrate the change in pH as carbonic acid is\u00a0formed.<strong> You will use the pH indicator phenol red, which turns yellow in acidic conditions and magenta (red-<\/strong><strong>purple) in basic conditions. <\/strong>\r\n<h3>Materials<\/h3>\r\n<ul>\r\n \t<li>Tap water<\/li>\r\n \t<li>Drinking straw<\/li>\r\n \t<li>Ehrlenmeyer flask (250 mL)<\/li>\r\n \t<li>Phenol red<\/li>\r\n \t<li>pH paper<\/li>\r\n<\/ul>\r\n<h3>Procedure<\/h3>\r\n<ol>\r\n \t<li>Obtain a small flask and a straw, and fill the flask approximately \u00bc full with tap water.<\/li>\r\n \t<li>Measure the pH of the water using the pH paper.<\/li>\r\n \t<li>Add 6\u20137 drops of phenol red to the flask.<\/li>\r\n \t<li>Do not swirl the flask (this may introduce CO<sub>2<\/sub> into the solution!), but agitate gently to mix the solution.<\/li>\r\n \t<li>Record the initial color of the water.<\/li>\r\n \t<li>Using a straw, blow air bubbles into the solution and observe any color changes.<\/li>\r\n \t<li>Record the final pH of the solution.<\/li>\r\n<\/ol>\r\n<h3>Data<\/h3>\r\n<table>\r\n<thead>\r\n<tr>\r\n<td><\/td>\r\n<th>Initial Solution<\/th>\r\n<th>Final Solution<\/th>\r\n<\/tr>\r\n<\/thead>\r\n<tbody>\r\n<tr>\r\n<th>pH<\/th>\r\n<td><\/td>\r\n<td><\/td>\r\n<\/tr>\r\n<tr>\r\n<th>Color<\/th>\r\n<td><\/td>\r\n<td><\/td>\r\n<\/tr>\r\n<\/tbody>\r\n<\/table>\r\n<\/div>\r\n<div>\r\n<h3>Lab Questions<\/h3>\r\n<ol>\r\n \t<li>What happens when carbon dioxide combines with water?<\/li>\r\n \t<li>Why did the phenol red solution turn color after you blew air bubbles into it?<\/li>\r\n \t<li>If a person holds her breath, CO<sub>2<\/sub> builds up in the bloodstream. What effect does this have on\u00a0blood pH?<\/li>\r\n \t<li>If a person hyperventilates, too much CO<sub>2<\/sub> is removed from the bloodstream. What effect does\u00a0this have on blood pH?<\/li>\r\n \t<li>Why is \"breathing into a bag\" a good treatment for a hyperventilating patient?<\/li>\r\n \t<li>Why is pH homeostasis so critical in living organisms?<\/li>\r\n<\/ol>\r\n<h2><strong>Part 4: Polar and Nonpolar Compounds <\/strong><\/h2>\r\n<a href=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/690\/2015\/07\/23014010\/Screen-Shot-2015-07-09-at-9.28.03-AM.png\"><img class=\"alignright size-full wp-image-35\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/690\/2015\/07\/23014010\/Screen-Shot-2015-07-09-at-9.28.03-AM.png\" alt=\"Screen Shot 2015-07-09 at 9.28.03 AM\" width=\"170\" height=\"161\" \/><\/a>Water is a fascinating molecule whose chemical structure is pretty much\u00a0responsible for life on earth. Chemical reactions that take place inside of a\u00a0cell exist in an aqueous environment consisting principally of water. The\u00a0primary characteristic of the water molecule that imparts its many unique\u00a0qualities is the simple fact that water is a polar molecule. When considering\u00a0the polarity of water, you must first remember that chemical bonds occur when\u00a02 or more atoms \"share\" electrons. In the water molecule, the oxygen atom\u00a0'hogs' the electrons it shares with the hydrogen ions. Because the electrons\u00a0are closer to the oxygen atom, that side of the water molecule ends up being\u00a0partially negative while the hydrogen side of the molecule ends up being\u00a0partially positive. This makes water an excellent solvent. Substances that are\u00a0hydrophilic (love water) are usually polar or ionic molecules themselves, and\u00a0will dissolve readily in water. Substances that are hydrophobic (hate water) are usually nonpolar molecules, and\u00a0will not dissolve in water. Nonpolar substances will dissolve in a nonpolar solvent such as oil.\u00a0Surfactants are special molecules that are both hydrophilic and hydrophobic. They allow water and oil to mix.\u00a0Soaps and detergents are both examples of surfactants.\r\n\r\n<\/div>\r\n<div>\r\n<h3>Materials<\/h3>\r\n<ul>\r\n \t<li>2 test tubes<\/li>\r\n \t<li>Oil<\/li>\r\n \t<li>Tap water<\/li>\r\n \t<li>Beet juice<\/li>\r\n \t<li>Chili oil<\/li>\r\n \t<li>Detergent<\/li>\r\n<\/ul>\r\n<h3>Procedure<\/h3>\r\n<ol>\r\n \t<li>Obtain two test tubes and add 5 ml of water and 5 ml of oil into each tube. Allow the tubes to stand for one minute. Record the appearance of the tubes and label the ingredients in the tube.<\/li>\r\n \t<li>Add \u22486 drops of beet juice extract to tube #1 and \u22486 drops of chili oil to tube #2. Allow diffusion to take place for 1\u20132 minutes. Record the appearance of the tubes.<\/li>\r\n \t<li>Shake each tube gently and let stand for several minutes. Record the appearance of the tubes.<\/li>\r\n \t<li>Next add a few drops of detergent to each tube; shake gently and observe. Record the appearance the tube.<\/li>\r\n<\/ol>\r\nDownload this page to <a href=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/690\/2016\/02\/23014012\/Step4.pdf\" target=\"_blank\" rel=\"noopener\">record the appearance of the tubes at every step<\/a>.\r\n\r\n<\/div>\r\n<h2><strong>Lab Questions <\/strong><\/h2>\r\n<ol>\r\n \t<li>What happens when lipids and water are combined? Why?<\/li>\r\n \t<li>How do beet juice extract and chili oil differ in their chemical properties? How do you know?<\/li>\r\n \t<li>Explain what happened when the tubes were shaken. What happened after the detergent was\u00a0added? How can you explain these results?<\/li>\r\n \t<li>How is the phospholipid bilayer that makes up a cell membrane both hydrophilic and\u00a0hydrophobic?<\/li>\r\n \t<li>What is a surfactant? How does it work?<\/li>\r\n<\/ol>\r\n<div><\/div>","rendered":"<div>\n<p>All life exists within the context of its environment. Each environment is characterized by its biological,\u00a0physical, and chemical properties. Since organisms are adapted to a specific environment, radical changes in\u00a0these conditions often result in injury to the individual or possibly extinction of the species. Recent reports of\u00a0declining frog populations, for example, have been correlated with increased ultraviolet radiation from the sun\u00a0(specifically UVB). Chemical reactions that take place inside of an organism are dependent upon both internal\u00a0and external chemical and physical properties. We will explore some of these properties in today&#8217;s lab.<\/p>\n<h2>Part 1: pH Chemistry<\/h2>\n<p>Although water is generally regarded as a stable compound, individual water molecules are constantly gaining,\u00a0losing, and swapping hydrogen atoms. This process is represented by the following chemical reaction:<\/p>\n<p style=\"text-align: center;\">H<sub>2<\/sub>O\u00a0\u2194\u00a0OH\u00a0+\u00a0H<\/p>\n<p>Pure water with a pH of 7 has equal numbers of hydrogen and hydroxide\u00a0ions at any given moment. Water is considered to be a neutral substance.\u00a0The pH of any solution can be determined by calculating the total\u00a0concentration of hydrogen ions in the solution.<\/p>\n<\/div>\n<div class=\"textbox shaded\">\n<h3><strong>What is a MOLE?<\/strong><\/h3>\n<p>A mole is a term used to describe\u00a0the quantity of something. If you\u00a0have a mole of paperclips, that\u00a0means you have paperclips. This\u00a0is similar to the way we use the word &#8220;dozen.&#8221; We know that if\u00a0you have a dozen paperclips, it\u00a0means you have 12 of them.<\/p>\n<p><strong>1 dozen = 12 <\/strong><\/p>\n<p><strong>1 mole = 6.02\u00d710<sub>23<\/sub><\/strong><\/p>\n<\/div>\n<div>\n<p>Scientists measure acidity using the pH scale. The pH scale ranges from 0 to 14, and the numbers represent the concentration of hydrogen ions<sub>\u20131<\/sub>\u00a0in the substance. For example, battery acid, with a pH of 1, has 1\u00d710\u00a0moles of hydrogen ions per liter of solution. Ammonia, which is a very\u00a0basic substance with a pH of 12, has 1\u00d710<sub>\u201312<\/sub> moles of hydrogen ions per\u00a0liter of solution. The more acidic the solution, the more hydrogen ions it\u00a0contains.<\/p>\n<\/div>\n<div>\n<p>Excessive changes in pH can cause metabolic and ecological problems.\u00a0For example, the pH of your blood is carefully kept between 7.35 and\u00a07.45. Any deviation above or below this range will result in alkalosis or acidosis, and both conditions can be\u00a0deadly. Acid rain, on the other hand, can dissolve toxic metals from the soil particles into the soil solution and\u00a0impair plant growth. As we will soon see, plant health is a factor that quickly affects most other life forms on\u00a0the planet.<\/p>\n<p><a href=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/690\/2015\/07\/23014011\/Screen-Shot-2015-07-09-at-10.04.56-AM.png\"><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter size-full wp-image-39\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/690\/2015\/07\/23014011\/Screen-Shot-2015-07-09-at-10.04.56-AM.png\" alt=\"Screen Shot 2015-07-09 at 10.04.56 AM\" width=\"884\" height=\"142\" \/><\/a><\/p>\n<\/div>\n<div>\n<h3>Materials<\/h3>\n<ul>\n<li>pH paper (1\u201314)<\/li>\n<li>Plastic tray with wells<\/li>\n<li>Wax pencil<\/li>\n<\/ul>\n<h3>Procedure<\/h3>\n<p>Following the instructions given by your teacher, measure the pH of each solution using pH paper. \u00a0Record the pH of these items below.<\/p>\n<ul>\n<li>Tap water<\/li>\n<li>Distilled water<\/li>\n<li>Bleach<\/li>\n<li>Aspirin<\/li>\n<li>Lemon juice<\/li>\n<li>Milk<\/li>\n<\/ul>\n<\/div>\n<div>\n<h2><strong>Part 2: Buffers <\/strong><\/h2>\n<p>Buffers are molecules that resist changes in pH. They can take up and release excess hydrogen ions in a\u00a0solution and therefore prevent drastic changes in pH, regardless of whether acid or base is added to the solution.\u00a0The net result is that the pH of the solution remains relatively stable (until the buffer is overwhelmed). Buffers\u00a0are commonly found in dissolved minerals, soils, and in living organisms.<\/p>\n<p>For example, buffers can play a protective role in lake ecosystems. In a lowland lake, acid rain causes very\u00a0little fluctuation in pH because these lakes are typically high in organic molecules that act as buffers. A lake\u00a0with little buffering capacity, such as a high alpine lake low in organic molecules, will experience a much\u00a0greater change in overall pH as a result of acid precipitation.<\/p>\n<h3>Materials<\/h3>\n<ul>\n<li>pH paper (1\u201314)<\/li>\n<li>Tap water (H<sub>2<\/sub>O)<\/li>\n<li>2 beakers (250 mL)<\/li>\n<li>1g NaHCO<sub>3<\/sub> (baking soda)<\/li>\n<li>0.001 M HCl (hydrochloric acid)<\/li>\n<li>Wax pencil<\/li>\n<\/ul>\n<h3>Procedure<\/h3>\n<ol>\n<li>Fill two beakers with 50 ml of tap water. Label one beaker &#8220;buffered&#8221; and label the other beaker\u00a0&#8220;unbuffered.&#8221;<\/li>\n<li>Add 1 gram of baking soda to the &#8220;buffered&#8221; beaker. Swirl to dissolve.<\/li>\n<li>Using the pH strips, measure the pH of both beakers. Record all measurements in Table 1.<\/li>\n<li>Add 10 ml of 0.001 M HCl (hydrochloric acid) to each beaker and swirl.<\/li>\n<li>Measure the pH of the two beakers and record.<\/li>\n<li>Repeat steps 3\u20135 until you have added a total of 50 ml of 0.001 M HCl to each beaker.<\/li>\n<\/ol>\n<h3>Data<\/h3>\n<p>Record the pH of your buffered and unbuffered solutions after each addition of 10 mL of hydrochloric\u00a0acid to each beaker.<\/p>\n<table>\n<thead>\n<tr>\n<th colspan=\"3\"><strong>Table 1. Buffered and Unbuffered Solutions<\/strong><\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<th rowspan=\"2\">Volume (mL) of<br \/>\n0.001 M HCl<\/th>\n<th colspan=\"2\">ph<\/th>\n<\/tr>\n<tr>\n<th>Buffered Solution<\/th>\n<th>Unbuffered Solution<\/th>\n<\/tr>\n<tr>\n<td style=\"text-align: center;\">0<\/td>\n<td><\/td>\n<td><\/td>\n<\/tr>\n<tr>\n<td style=\"text-align: center;\">10<\/td>\n<td><\/td>\n<td><\/td>\n<\/tr>\n<tr>\n<td style=\"text-align: center;\">20<\/td>\n<td><\/td>\n<td><\/td>\n<\/tr>\n<tr>\n<td style=\"text-align: center;\">30<\/td>\n<td><\/td>\n<td><\/td>\n<\/tr>\n<tr>\n<td style=\"text-align: center;\">40<\/td>\n<td><\/td>\n<td><\/td>\n<\/tr>\n<tr>\n<td style=\"text-align: center;\">50<\/td>\n<td><\/td>\n<td><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<h3>Data Analysis<\/h3>\n<div>\n<p>Illustrate the buffering capacity of each solution by graphing your results below. Place the volume of \u00a0HCl on the x-axis and the pH value on the y-axis. Don&#8217;t forget to give your graph a title.<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"alignnone wp-image-34 size-full\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/690\/2015\/07\/23014009\/Screen-Shot-2015-07-09-at-9.23.59-AM.png\" alt=\"Screen Shot 2015-07-09 at 9.23.59 AM\" width=\"650\" height=\"265\" \/><\/p>\n<p>You can download this\u00a0<a href=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/690\/2016\/02\/23014129\/GraphPaper.pdf\">graph paper template<\/a>\u00a0to complete this portion.<\/p>\n<\/div>\n<div>\n<h2><strong>Part 3: Buffers in the Blood <\/strong><\/h2>\n<p>Bicarbonate ions act as a powerful buffer in your blood. They are created when carbon dioxide (CO<sub>2<\/sub>), produced\u00a0during cellular respiration, reacts with water:<\/p>\n<p>CO<sub>2\u00a0<\/sub>+ H<sub>2<\/sub>O \u2194 H<sub>2<\/sub>CO<sub>3<\/sub> \u2194 HCO<sub>3\u2013<\/sub>+\u00a0H+<\/p>\n<p>Notice that hydrogen ions are also generated, which increases the acidity of blood and decreases the pH. In\u00a0your body, the hydrogen ions are absorbed by hemoglobin molecules on your red blood cells. Meanwhile, the\u00a0bicarbonate ions circulate in the blood plasma, preventing rapid pH changes. As your blood circulates past the\u00a0metabolizing cells, more and more CO<sub>2<\/sub> enters your bloodstream and turns to bicarbonate ions. By the time the\u00a0blood reaches the lungs, it is full of bicarbonate and hydrogen ions. The bicarbonate and hydrogen ions now\u00a0combine and the reaction goes from right to left, releasing the CO<sub>2<\/sub>, which is now breathed out.\u00a0In this exercise, you will bubble CO<sub>2<\/sub> into tap water and demonstrate the change in pH as carbonic acid is\u00a0formed.<strong> You will use the pH indicator phenol red, which turns yellow in acidic conditions and magenta (red-<\/strong><strong>purple) in basic conditions. <\/strong><\/p>\n<h3>Materials<\/h3>\n<ul>\n<li>Tap water<\/li>\n<li>Drinking straw<\/li>\n<li>Ehrlenmeyer flask (250 mL)<\/li>\n<li>Phenol red<\/li>\n<li>pH paper<\/li>\n<\/ul>\n<h3>Procedure<\/h3>\n<ol>\n<li>Obtain a small flask and a straw, and fill the flask approximately \u00bc full with tap water.<\/li>\n<li>Measure the pH of the water using the pH paper.<\/li>\n<li>Add 6\u20137 drops of phenol red to the flask.<\/li>\n<li>Do not swirl the flask (this may introduce CO<sub>2<\/sub> into the solution!), but agitate gently to mix the solution.<\/li>\n<li>Record the initial color of the water.<\/li>\n<li>Using a straw, blow air bubbles into the solution and observe any color changes.<\/li>\n<li>Record the final pH of the solution.<\/li>\n<\/ol>\n<h3>Data<\/h3>\n<table>\n<thead>\n<tr>\n<td><\/td>\n<th>Initial Solution<\/th>\n<th>Final Solution<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<th>pH<\/th>\n<td><\/td>\n<td><\/td>\n<\/tr>\n<tr>\n<th>Color<\/th>\n<td><\/td>\n<td><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<div>\n<h3>Lab Questions<\/h3>\n<ol>\n<li>What happens when carbon dioxide combines with water?<\/li>\n<li>Why did the phenol red solution turn color after you blew air bubbles into it?<\/li>\n<li>If a person holds her breath, CO<sub>2<\/sub> builds up in the bloodstream. What effect does this have on\u00a0blood pH?<\/li>\n<li>If a person hyperventilates, too much CO<sub>2<\/sub> is removed from the bloodstream. What effect does\u00a0this have on blood pH?<\/li>\n<li>Why is &#8220;breathing into a bag&#8221; a good treatment for a hyperventilating patient?<\/li>\n<li>Why is pH homeostasis so critical in living organisms?<\/li>\n<\/ol>\n<h2><strong>Part 4: Polar and Nonpolar Compounds <\/strong><\/h2>\n<p><a href=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/690\/2015\/07\/23014010\/Screen-Shot-2015-07-09-at-9.28.03-AM.png\"><img loading=\"lazy\" decoding=\"async\" class=\"alignright size-full wp-image-35\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/690\/2015\/07\/23014010\/Screen-Shot-2015-07-09-at-9.28.03-AM.png\" alt=\"Screen Shot 2015-07-09 at 9.28.03 AM\" width=\"170\" height=\"161\" \/><\/a>Water is a fascinating molecule whose chemical structure is pretty much\u00a0responsible for life on earth. Chemical reactions that take place inside of a\u00a0cell exist in an aqueous environment consisting principally of water. The\u00a0primary characteristic of the water molecule that imparts its many unique\u00a0qualities is the simple fact that water is a polar molecule. When considering\u00a0the polarity of water, you must first remember that chemical bonds occur when\u00a02 or more atoms &#8220;share&#8221; electrons. In the water molecule, the oxygen atom\u00a0&#8216;hogs&#8217; the electrons it shares with the hydrogen ions. Because the electrons\u00a0are closer to the oxygen atom, that side of the water molecule ends up being\u00a0partially negative while the hydrogen side of the molecule ends up being\u00a0partially positive. This makes water an excellent solvent. Substances that are\u00a0hydrophilic (love water) are usually polar or ionic molecules themselves, and\u00a0will dissolve readily in water. Substances that are hydrophobic (hate water) are usually nonpolar molecules, and\u00a0will not dissolve in water. Nonpolar substances will dissolve in a nonpolar solvent such as oil.\u00a0Surfactants are special molecules that are both hydrophilic and hydrophobic. They allow water and oil to mix.\u00a0Soaps and detergents are both examples of surfactants.<\/p>\n<\/div>\n<div>\n<h3>Materials<\/h3>\n<ul>\n<li>2 test tubes<\/li>\n<li>Oil<\/li>\n<li>Tap water<\/li>\n<li>Beet juice<\/li>\n<li>Chili oil<\/li>\n<li>Detergent<\/li>\n<\/ul>\n<h3>Procedure<\/h3>\n<ol>\n<li>Obtain two test tubes and add 5 ml of water and 5 ml of oil into each tube. Allow the tubes to stand for one minute. Record the appearance of the tubes and label the ingredients in the tube.<\/li>\n<li>Add \u22486 drops of beet juice extract to tube #1 and \u22486 drops of chili oil to tube #2. Allow diffusion to take place for 1\u20132 minutes. Record the appearance of the tubes.<\/li>\n<li>Shake each tube gently and let stand for several minutes. Record the appearance of the tubes.<\/li>\n<li>Next add a few drops of detergent to each tube; shake gently and observe. Record the appearance the tube.<\/li>\n<\/ol>\n<p>Download this page to <a href=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/690\/2016\/02\/23014012\/Step4.pdf\" target=\"_blank\" rel=\"noopener\">record the appearance of the tubes at every step<\/a>.<\/p>\n<\/div>\n<h2><strong>Lab Questions <\/strong><\/h2>\n<ol>\n<li>What happens when lipids and water are combined? Why?<\/li>\n<li>How do beet juice extract and chili oil differ in their chemical properties? How do you know?<\/li>\n<li>Explain what happened when the tubes were shaken. What happened after the detergent was\u00a0added? How can you explain these results?<\/li>\n<li>How is the phospholipid bilayer that makes up a cell membrane both hydrophilic and\u00a0hydrophobic?<\/li>\n<li>What is a surfactant? How does it work?<\/li>\n<\/ol>\n<div><\/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-33\">\n\t\t\t\t\t\t\t <div class=\"licensing\"><div class=\"license-attribution-dropdown-subheading\">CC licensed content, Original<\/div><ul class=\"citation-list\"><li>Biology Labs. <strong>Authored by<\/strong>: Wendy Riggs. <strong>Provided by<\/strong>: College of the Redwoods. <strong>Located at<\/strong>: <a target=\"_blank\" href=\"http:\/\/www.redwoods.edu\/\">http:\/\/www.redwoods.edu\/<\/a>. <strong>License<\/strong>: <em><a target=\"_blank\" rel=\"license\" href=\"https:\/\/creativecommons.org\/licenses\/by\/4.0\/\">CC BY: Attribution<\/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":78,"menu_order":3,"template":"","meta":{"_candela_citation":"[{\"type\":\"original\",\"description\":\"Biology Labs\",\"author\":\"Wendy Riggs\",\"organization\":\"College of the Redwoods\",\"url\":\"www.redwoods.edu\/\",\"project\":\"\",\"license\":\"cc-by\",\"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-33","chapter","type-chapter","status-publish","hentry"],"part":436,"_links":{"self":[{"href":"https:\/\/courses.lumenlearning.com\/biolabs1\/wp-json\/pressbooks\/v2\/chapters\/33","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/courses.lumenlearning.com\/biolabs1\/wp-json\/pressbooks\/v2\/chapters"}],"about":[{"href":"https:\/\/courses.lumenlearning.com\/biolabs1\/wp-json\/wp\/v2\/types\/chapter"}],"author":[{"embeddable":true,"href":"https:\/\/courses.lumenlearning.com\/biolabs1\/wp-json\/wp\/v2\/users\/78"}],"version-history":[{"count":10,"href":"https:\/\/courses.lumenlearning.com\/biolabs1\/wp-json\/pressbooks\/v2\/chapters\/33\/revisions"}],"predecessor-version":[{"id":453,"href":"https:\/\/courses.lumenlearning.com\/biolabs1\/wp-json\/pressbooks\/v2\/chapters\/33\/revisions\/453"}],"part":[{"href":"https:\/\/courses.lumenlearning.com\/biolabs1\/wp-json\/pressbooks\/v2\/parts\/436"}],"metadata":[{"href":"https:\/\/courses.lumenlearning.com\/biolabs1\/wp-json\/pressbooks\/v2\/chapters\/33\/metadata\/"}],"wp:attachment":[{"href":"https:\/\/courses.lumenlearning.com\/biolabs1\/wp-json\/wp\/v2\/media?parent=33"}],"wp:term":[{"taxonomy":"chapter-type","embeddable":true,"href":"https:\/\/courses.lumenlearning.com\/biolabs1\/wp-json\/pressbooks\/v2\/chapter-type?post=33"},{"taxonomy":"contributor","embeddable":true,"href":"https:\/\/courses.lumenlearning.com\/biolabs1\/wp-json\/wp\/v2\/contributor?post=33"},{"taxonomy":"license","embeddable":true,"href":"https:\/\/courses.lumenlearning.com\/biolabs1\/wp-json\/wp\/v2\/license?post=33"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}