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Overview of Module 4

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Overview of Module 4

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    1. Overview of Module 4 By the end of this module, you will be able to Describe the polarity of water and draw the hydrogen bond. Describe the properties of water as a result of its polarity. Define the terms acid, base, pH and hydrogen ion or proton. Relate pH to the concentration of hydrogen ions. Read a pH scale. Define the term buffer and describe how buffers work to keep the pH within a narrow range.

    2. Module 4 Water, Acids & Bases, pH and Buffers

    3. Sections for this module Water is a polar molecule Properties of water Acids and Bases pH Buffers There are five sections in this module. Section I is titled Water is a polar molecule. Section II is the properties of water. Section III are on acids and bases. Section IV is on pH and the last section is on buffers.There are five sections in this module. Section I is titled Water is a polar molecule. Section II is the properties of water. Section III are on acids and bases. Section IV is on pH and the last section is on buffers.

    4. I. Water is a polar molecule Section I: Water is a polar molecule Section I: Water is a polar molecule

    5. The Shape of Water Water or H2O is made by the covalent bonds between 2 Hydrogen's and the Oxygen The 2 Hydrogen's attached to the Oxygen at an angle of 107.5o O or H H Water or H2O is made by the covalent bonds between 2 hydrogen atoms attached to the oxygen. Because of the other four electrons in the second orbital of oxygen, the hydrogens are bonded to the oxygen at an angle of 107.5 degrees. This gives water its shape as shown.Water or H2O is made by the covalent bonds between 2 hydrogen atoms attached to the oxygen. Because of the other four electrons in the second orbital of oxygen, the hydrogens are bonded to the oxygen at an angle of 107.5 degrees. This gives water its shape as shown.

    6. Electronegativity In living systems, Oxygen & Nitrogen are electronegative. They pull the electrons of the covalent bond closer to their nuclei, giving O and N a partial negative charge. The attached Hydrogen's therefore have a partial positive charge. Electronegativity is the property of oxygen and nitrogen in living organisms in which these atoms pull the electrons of the covalent bond closer to their nuclei. This gives oxygen and nitrogen a partial negative charge due to the increased presence of the electrons. As a result the electrons are further from the hydrogens that are attached, giving them a partial positive charge.Electronegativity is the property of oxygen and nitrogen in living organisms in which these atoms pull the electrons of the covalent bond closer to their nuclei. This gives oxygen and nitrogen a partial negative charge due to the increased presence of the electrons. As a result the electrons are further from the hydrogens that are attached, giving them a partial positive charge.

    7. Water is a Polar Molecule Water’s shape and the electronegativity of oxygen means that the O is partially negative and the H’s are each partially positive. Therefore water looks like a tiny V-shaped magnet Negative pole at O Positive poles at each H Water’s shape and the electronegativity of oxygen means that in water, the oxygen is partly negative and each of the hydrogens are partially positive. Therefore water looks and acts as a tiny v-shaped magnet with the negative pole of the water “magnet” at the oxygen and the positive poles at the hydrogens.Water’s shape and the electronegativity of oxygen means that in water, the oxygen is partly negative and each of the hydrogens are partially positive. Therefore water looks and acts as a tiny v-shaped magnet with the negative pole of the water “magnet” at the oxygen and the positive poles at the hydrogens.

    8. The Poles of Water These are the poles of the water “magnet”These are the poles of the water “magnet”

    9. The Hydrogen Bond For any molecules with at least 1 H attached to an O (or a N) The – O of 1 molecule is attracted to the + H of another molecule. An attraction of the opposite poles Acts like molecular magnets Not a true bond—just an attraction Very weak and short-lived But additive to make overall strong effect As with other magnets, opposite poles in two molecules of water are attracted to each other. The negative oxygen of one water is attracted to the positive hydrogen of another. Notes that this is not a true bond but rather a weak and short-lived attraction of the pole of one molecule to the opposite pole of another molecule. However, even though each hydrogen bond is weak, they can add up to make an overall strong effect.As with other magnets, opposite poles in two molecules of water are attracted to each other. The negative oxygen of one water is attracted to the positive hydrogen of another. Notes that this is not a true bond but rather a weak and short-lived attraction of the pole of one molecule to the opposite pole of another molecule. However, even though each hydrogen bond is weak, they can add up to make an overall strong effect.

    10. Hydrogen Bonds of Water This shows the hydrogen bonds between five different water molecules. Since the water molecules are constantly in motion, the next time we look at these molecules, they will show a slightly different arrangement of hydrogen bonds. The bonds shown here have broken and other bonds will have formed.This shows the hydrogen bonds between five different water molecules. Since the water molecules are constantly in motion, the next time we look at these molecules, they will show a slightly different arrangement of hydrogen bonds. The bonds shown here have broken and other bonds will have formed.

    11. Concept Check Which of these molecules are polar? a) CH3CH2-O-H b) CH3CH2-N-H H H c) H-C=O

    12. Concept Check Answers a) Ethyl alcohol is polar because of –O-H (This is the alcohol of wine, liquor, etc which of course is very soluble in water) b) Ethyl amine is polar because of –N-H (This is a brain chemical released when we are in love) c) Formaldehyde is NOT polar because there is no H attached to the O

    13. II. Properties of Water Section II: Properties of waterSection II: Properties of water

    14. Life-Giving Properties of Water There are 6 properties of water that result from its hydrogen bonds: Surface tension Adhesion and cohesion High specific heat High heat of vaporization Ice floats Solvent of life There are six properties of water resulting from its hydrogen bonds that are necessary for life on earth. We will look at each of these separately.There are six properties of water resulting from its hydrogen bonds that are necessary for life on earth. We will look at each of these separately.

    15. 1. Surface Tension At the surface, water makes Hydrogen bonds with itself but not the air This acts as an invisible film Surface tension makes water form drops Organisms like the water strider can live on the water Surface Tension. At the surface, water makes hydrogen bonds with itself but not the air, creating an invisible film. Surface tension also makes water form drops. Organisms like the water strider live their entire lives on the surface of the water, using the surface tension to keep them from sinking.Surface Tension. At the surface, water makes hydrogen bonds with itself but not the air, creating an invisible film. Surface tension also makes water form drops. Organisms like the water strider live their entire lives on the surface of the water, using the surface tension to keep them from sinking.

    16. Examples of Surface Tension Water drops on a leaf or the water strider on a pond are examples of surface tension of water due to hydrogen bonding.Water drops on a leaf or the water strider on a pond are examples of surface tension of water due to hydrogen bonding.

    17. 2. Adhesion and Cohesion Water sticks to itself by hydrogen bonds—cohesion Water adheres to other polar molecules—adhesion Using adhesion and cohesion, trees can bring water from their roots to their leaves. Cohesion is when water sticks to itself through hydrogen bonds. Adhesion is when water adheres to other polar molecules. By using adhesion of the water to the sides of the xylem and cohesion of water molecules to each other, water is able to travel from the roots to the tops of trees.Cohesion is when water sticks to itself through hydrogen bonds. Adhesion is when water adheres to other polar molecules. By using adhesion of the water to the sides of the xylem and cohesion of water molecules to each other, water is able to travel from the roots to the tops of trees.

    18. 3. High Specific Heat For water to boil, it must be moving fast enough to break the hydrogen bonds keeping it liquid so it can become steam. It takes a lot of heat to get water moving that quickly. This is the high specific heat. This means that water is slow to heat up and evaporate and also slow to cool down and freeze. Life can exist on most of the earth because of water’s high specific heat. In order for water to boil, it must be moving fast enough to break the hydrogen bonds holding it in the liquid state so it can go up in the atmosphere as steam. It takes a great deal of heat to get water moving that quickly. This is what is meant by high specific heat. In fact it takes 1 calorie of heat to raise 1 cc of water 1o C. Since it takes so much specific heat to increase the temperature of water, this means that water is slow to heat up and evaporate. A watched pot never boils. Equally water is slow to cool down and freeze. Lake Travis is cold for swimming in March but is much warmer in September after the hot summer. Because of high specific heat, water stays liquid over a very wide range of temperatures, making it possible for life to exist on most of the earth.In order for water to boil, it must be moving fast enough to break the hydrogen bonds holding it in the liquid state so it can go up in the atmosphere as steam. It takes a great deal of heat to get water moving that quickly. This is what is meant by high specific heat. In fact it takes 1 calorie of heat to raise 1 cc of water 1o C. Since it takes so much specific heat to increase the temperature of water, this means that water is slow to heat up and evaporate. A watched pot never boils. Equally water is slow to cool down and freeze. Lake Travis is cold for swimming in March but is much warmer in September after the hot summer. Because of high specific heat, water stays liquid over a very wide range of temperatures, making it possible for life to exist on most of the earth.

    19. 4. High Heat of Vaporization People and other organisms can use water’s high specific heat to cool themselves. We open sweat glands on our skin to allow water to evaporate taking excess body heat with it. Without perspiration (sweating), we can overheat and die. Sweat has to evaporate to cool us; it cannot cool if it just collects as liquid on the body. High Heat of Vaporization is related to high specific heat. People and other organisms can use water’s high specific heat to cool themselves. By opening sweat glands on our skin, we allow water to evaporate taking the excess body heat with it. If we cannot sweat, we can overheat and die.High Heat of Vaporization is related to high specific heat. People and other organisms can use water’s high specific heat to cool themselves. By opening sweat glands on our skin, we allow water to evaporate taking the excess body heat with it. If we cannot sweat, we can overheat and die.

    20. Perspiration Perspiration appears when we heat up the body through exercise or work.Perspiration appears when we heat up the body through exercise or work.

    21. 5. Ice Floats There are fewer hydrogen bonds in ice and they are further apart so ice floats. Important for fish and other organisms living in fresh water in the winter. One reason the polar bear is endangered is that global warming is melting the ice from which it hunts. There are fewer hydrogen bonds in ice and they are further apart, so ice is less dense than water and ice floats. This is important for fish, turtles and other aquatic animals that depend on having liquid water under the ice to survive the winter. Polar bears use the ice as a platform from which to hunt seals. They wait at air holes in the ice for seals to appear. With global warming , the ice is shrinking and with it, the air holes that the polar bears depend upon.There are fewer hydrogen bonds in ice and they are further apart, so ice is less dense than water and ice floats. This is important for fish, turtles and other aquatic animals that depend on having liquid water under the ice to survive the winter. Polar bears use the ice as a platform from which to hunt seals. They wait at air holes in the ice for seals to appear. With global warming , the ice is shrinking and with it, the air holes that the polar bears depend upon.

    22. Polar Bear on Remnant of Ice This polar bear is doomed to starvation.This polar bear is doomed to starvation.

    23. 6. Solvent of Life Hydrophilic molecules are “water-loving” Ions such as Na+, K+, Ca++, Cl- Polar molecules such as glucose, amino acids Hydrophilic molecules can dissolve in water. (Hydrophobic molecules are “water-fearing” like oil and cannot dissolve in water.) The final property of water is that many molecules dissolve in water. Water-loving or hydrophilic molecules include ions and polar molecules such as glucose or amino acids. These easily dissolve in water. Remember that hydrophobic or water-hating molecules such as oils cannot dissolve in water.The final property of water is that many molecules dissolve in water. Water-loving or hydrophilic molecules include ions and polar molecules such as glucose or amino acids. These easily dissolve in water. Remember that hydrophobic or water-hating molecules such as oils cannot dissolve in water.

    24. Sodium Chloride in Water When the molecule sodium chloride, NaCl, hits the water, it separates into the sodium ions and chloride ions. The positive sodium ions –blue--are surrounded with water molecules with the negative oxygens facing the sodium. The negative chloride ions –green--are surrounded by water molecules with the positive hydrogens facing the chlorides. Other ions will behave similarly.When the molecule sodium chloride, NaCl, hits the water, it separates into the sodium ions and chloride ions. The positive sodium ions –blue--are surrounded with water molecules with the negative oxygens facing the sodium. The negative chloride ions –green--are surrounded by water molecules with the positive hydrogens facing the chlorides. Other ions will behave similarly.

    25. Summary of Sections I and II Water is polar with a – O and 2 + H’s. The opposite poles of water are attracted to each other to make hydrogen bonds. Hydrogen bonds are weak and short-lived but cumulative. The cumulative effects of hydrogen bonds give water its life-giving properties. Summary of Sections I and II. Water is a polar molecules with a negative oxygen and two positive hydrogens. The opposite poles of water are attracted to each other creating hydrogen bonds. These magnetic attractions, hydrogen bonds, are weak and short-lived but are cumulative and add up. The cumulative effects of hydrogen bonds give water its life-giving properties.Summary of Sections I and II. Water is a polar molecules with a negative oxygen and two positive hydrogens. The opposite poles of water are attracted to each other creating hydrogen bonds. These magnetic attractions, hydrogen bonds, are weak and short-lived but are cumulative and add up. The cumulative effects of hydrogen bonds give water its life-giving properties.

    26. III. Acids & Bases Section III: Acids and BasesSection III: Acids and Bases

    27. Dissociation of Water In 1 in every 107 molecules, the O of a water molecule pulls off an H of the other. H2O + H2O ? OH- + H3O+ hydroxide hydronium ion ion In 1 in every 10 million or 107 molecules, the oxygen of one molecule of water pulls off one of the hydrogens from another molecule of water. This may be written as two molecules of water will react to form a negatively-charged hydroxide ion and a positively-charged hydronium ion.In 1 in every 10 million or 107 molecules, the oxygen of one molecule of water pulls off one of the hydrogens from another molecule of water. This may be written as two molecules of water will react to form a negatively-charged hydroxide ion and a positively-charged hydronium ion.

    28. Dissociation of other molecules Other molecules can dissociate in water. In the example below, hydrochloric acid (HCl) dissociates and donates its proton, or H+ to ammonia (NH3) to make ammonium ion (NH4+) HCl + NH3 ? Cl- + NH4+ Other molecules may also dissociate in water. For example, hydrochloric acid, HCl, dissociates and donates its proton or H+ to ammonia, NH3 to make an ammonium ion.Other molecules may also dissociate in water. For example, hydrochloric acid, HCl, dissociates and donates its proton or H+ to ammonia, NH3 to make an ammonium ion.

    29. Anions and Cations An anion is a negatively charged ion Cl-, OH-, HCOO- are all anions A cation is a positively charged ion NH4+, Ca2+, Na+ are all cations Another term for a negatively charged ion is an anion. Here are some examples of anions. Another term for a positively charged ion is a cation. Here are some cations. Anions and cations are very important in living organisms.Another term for a negatively charged ion is an anion. Here are some examples of anions. Another term for a positively charged ion is a cation. Here are some cations. Anions and cations are very important in living organisms.

    30. Definitions In the Bronsted-Lowry definition of acids and bases, an acid donates a proton or H+ a base accepts a proton or H+ There are several definitions for an acid or a base. The Bronsted-Lowry definition is often used in biological systems. The Bronsted-Lowry definition is that an acid donates a proton or hydrogen ion and a base accepts a proton or hydrogen ion.There are several definitions for an acid or a base. The Bronsted-Lowry definition is often used in biological systems. The Bronsted-Lowry definition is that an acid donates a proton or hydrogen ion and a base accepts a proton or hydrogen ion.

    31. Acids and Bases In the equation HCl + NH3 ? Cl- + NH4+ HCl donates the H+ and so is the acid NH3 accepts the H+ and so is the base In this equation, the HCl is an acid, donating its proton to give the chloride ion. Ammonia, NH3, is the base and accepts the proton to make ammonium ion.In this equation, the HCl is an acid, donating its proton to give the chloride ion. Ammonia, NH3, is the base and accepts the proton to make ammonium ion.

    32. A Note About Nomenclature Hydrogen has 1 proton and 1 electron. When a molecule like H2O or HCl dissociates, the electron stays behind so only the proton is donated. Therefore, the terms below mean the same thing: H+ (pronounced “H plus”) Hydrogen ion proton A note about nomenclature. A Hydrogen atom has one proton and one electron. When a molecule like water or hydrochloric acid dissociates, the electron stays behind and only the proton is donated. Therefore the following terms all mean the same thing: H plus, hydrogen ion and proton.A note about nomenclature. A Hydrogen atom has one proton and one electron. When a molecule like water or hydrochloric acid dissociates, the electron stays behind and only the proton is donated. Therefore the following terms all mean the same thing: H plus, hydrogen ion and proton.

    33. Concept Check Identify the acid and base for each of the equations below: CH3COOH + OH- ? CH3COO- + H2O H2SO4 + NH3 ? HSO4- + NH4+

    34. Concept Check Answers a) CH3COOH + OH- ? CH3COO- + H2O Acid Base (The acid is acetic acid or vinegar; the base is hydroxide ion from molecules such as sodium hydroxide, NaOH, or lye.) b) H2SO4 + NH3 ? HSO4- + NH4+ Acid Base (The acid is sulfuric acid, a very strong acid)

    35. IV. pH and ph scales Section IV: pH and pH scalesSection IV: pH and pH scales

    36. pH Nomenclature pH relates to the strength of an acid or the concentration of H+ in a solution We use square brackets [ ]to mean concentration Therefore pH relates to [H+] in a solution. The pH relates to the strength of an acid, or t he concentration of hydrogen ions in a solution. In science, we use square brackets to indicated concentration. Therefore pH relates to the concentration of hydrogen ions in a solution.The pH relates to the strength of an acid, or t he concentration of hydrogen ions in a solution. In science, we use square brackets to indicated concentration. Therefore pH relates to the concentration of hydrogen ions in a solution.

    37. Determining pH [H+] of acid A = 10-6 M or 0.000001 M [H+] of acid B = 10-2 M or 0.01 M Acid B is a stronger acid than acid A. The pH is the exponent of the [H+] so the pH of acid A is 6 and the pH of acid B is 2 Acid B is 104 times more acidic than acid A In an example, the concentration of hydrogen ions in a solution of acid A is 10-6 M or 0.0000001 M. The concentration of hydrogen ions in a solution of acid B is 10-2 M or 0.01 M. Therefore acid B is a stronger acid than acid A. In the pH scale, the pH is the exponent of the concentration of hydrogen ions. The pH of acid A is 6 and the pH of acid B is 2. Acid B is 10,000 or 104 times more acidic than acid A.In an example, the concentration of hydrogen ions in a solution of acid A is 10-6 M or 0.0000001 M. The concentration of hydrogen ions in a solution of acid B is 10-2 M or 0.01 M. Therefore acid B is a stronger acid than acid A. In the pH scale, the pH is the exponent of the concentration of hydrogen ions. The pH of acid A is 6 and the pH of acid B is 2. Acid B is 10,000 or 104 times more acidic than acid A.

    38. pH scale pH scale ranges from 1 to 14 pH of 1-7 is acidic with the smaller number being more acidic pH of 7-14 is basic (or alkaline) with the larger number being more basic. pH 7, the dissociation of water, is neutral. The pH scale ranges from 1 to 14. Solutions with a pH of between 1 and 7 are acidic with the smaller number being the more acidic. The pH of a solution between 7 and 14 is basic or alkaline with the lager number being the more basic. A solution of pH 7, the dissociation of water, is neutral, neither acidic nor basic.The pH scale ranges from 1 to 14. Solutions with a pH of between 1 and 7 are acidic with the smaller number being the more acidic. The pH of a solution between 7 and 14 is basic or alkaline with the lager number being the more basic. A solution of pH 7, the dissociation of water, is neutral, neither acidic nor basic.

    39. The pH Scale Here is an illustration of the pH scale, with the acids on the left and the bases on the right. For example, lemons, vinegar, apples and tomatoes are acids and soap, ammonia and drain cleaners are bases. Note that foods are frequently acids and cleaners are frequently bases.Here is an illustration of the pH scale, with the acids on the left and the bases on the right. For example, lemons, vinegar, apples and tomatoes are acids and soap, ammonia and drain cleaners are bases. Note that foods are frequently acids and cleaners are frequently bases.

    40. Measuring pH pH paper with chemicals to indicate pH pH meter whose electrode measures [H+] Here are two ways to measure pH. On the left is pH paper with chemicals in the paper to indicate the pH of a solution. On the right is a pH meter. The electrode is placed in a solution and measures the amount of hydrogen ions, recorded as pH.Here are two ways to measure pH. On the left is pH paper with chemicals in the paper to indicate the pH of a solution. On the right is a pH meter. The electrode is placed in a solution and measures the amount of hydrogen ions, recorded as pH.

    41. Mixing acids and bases If you mix an equal amount of an acid of pH 4 and a base of pH 10 you get pH 7. (pH 4 + pH 10)/2 = pH 7 Your stomach has HCl of pH 1-2 in it. If your stomach is too acidic, you can take baking soda of pH 8.5 to neutralize the stomach acids. We call products like baking soda antacids (“anti-acids”) If you mix an equal amount of a an acid of pH 4 and a base of pH 10, you will get pH 7, the average of the two. For example, your stomach as hydrochloric acid of pH one in it. If your stomach goes lower than pH one and becomes too acid, you can take baking soda of pH 8.5 to neutralize the stomach acids. We call products that neutralize the acids antacids, a contraction of “anti-acids.”If you mix an equal amount of a an acid of pH 4 and a base of pH 10, you will get pH 7, the average of the two. For example, your stomach as hydrochloric acid of pH one in it. If your stomach goes lower than pH one and becomes too acid, you can take baking soda of pH 8.5 to neutralize the stomach acids. We call products that neutralize the acids antacids, a contraction of “anti-acids.”

    42. Concept Check 1. Lemon juice is pH 2. What is its [H+]? Tomatoes are pH 4. How much more acid is lemon juice than a tomato? 2. Blood is normally in the range of pH 7.35 to 7.45. Is this considered acidic or basic? If blood has a pH 7.6, is this more basic or acidic than normal?

    43. Concept Check Answers 1. [H+] of lemon juice is 0.01 M or 10-2M Lemon juice is 100 times more acidic than a tomato with [H+] = 10-4M 2. Blood is slightly basic (alkaline) at pH 7.35-7.45 It becomes more basic (alkaline) at pH 7.6

    44. pOH Occasionally the concentration of OH-, [OH-], is used to determine pOH. This scale also goes from 1-14 with 1 being the most basic or alkaline and 14 being the least basic or alkaline. Occasionally, the concentration of hydroxide or OH minus ion is used to get the pOH. This scale also goes fro 1 to 14 with 1 being the most basic or alkaline and 14 being the least basic or alkaline.Occasionally, the concentration of hydroxide or OH minus ion is used to get the pOH. This scale also goes fro 1 to 14 with 1 being the most basic or alkaline and 14 being the least basic or alkaline.

    45. V. Buffers Section V: BuffersSection V: Buffers

    46. Definition of a Buffer A buffer is a combination of a weak acid and base that is in equilibrium. This maintains the solution within a narrow pH range. Analogous to your money. If you need cash, [H+], then you get some from the bank. If you have extra cash ?, [H+], you deposit it in the bank. A buffer is a combination of a weak acid and base that is in equilibrium. This maintains the solution within a narrow pH range. That analogy is your money. If you need cash, or hydrogen ions, then you get some from the bank or buffer. If you have extra cash or hydrogen ions, you deposit into your account in the bank.A buffer is a combination of a weak acid and base that is in equilibrium. This maintains the solution within a narrow pH range. That analogy is your money. If you need cash, or hydrogen ions, then you get some from the bank or buffer. If you have extra cash or hydrogen ions, you deposit into your account in the bank.

    47. The Buffering System of Blood I Blood must stay within the pH range of 7.2 – 7.6, preferably close to 7.35-7.45. Death can result if pH becomes too acidic at 6.8 or too alkaline at 7.8. However, CO2 released by the cells makes the blood more basic and nutrients and lactic acid can make the blood more acidic. Let’s use the buffering system of Blood as an example. Blood must stay within the pH range of 7.2 to 7.6, preferably close to 7.4. Death can result if pH becomes too acidic at 6.7 or too alkaline at 7.8. However, carbon dioxide released by the cells makes the blood more basic and nutrients. Conversely, lactic acid can make the blood more acidic.Let’s use the buffering system of Blood as an example. Blood must stay within the pH range of 7.2 to 7.6, preferably close to 7.4. Death can result if pH becomes too acidic at 6.7 or too alkaline at 7.8. However, carbon dioxide released by the cells makes the blood more basic and nutrients. Conversely, lactic acid can make the blood more acidic.

    48. The Buffering System of Blood II There is a carbonate-bicarbonate buffer: H+ + HCO3- H2CO3 H2O + CO2 If the blood is too acidic, the excess H+ will be absorbed. If the blood is too basic (alkaline), then H+ will be released. In blood t here is a buffering system to keep the pH within a narrow range. This is a carbonate=bicarbonate buffer.. Hydrogen ions and carbonate, are in equilibrium with bicarbonate. Bicarbonate is in equilibrium with water and carbon dioxide. If the blood is too acidic, the excess hydrogen ions will be absorbed. If the blood is too basic, then the hydrogen ions will be released.In blood t here is a buffering system to keep the pH within a narrow range. This is a carbonate=bicarbonate buffer.. Hydrogen ions and carbonate, are in equilibrium with bicarbonate. Bicarbonate is in equilibrium with water and carbon dioxide. If the blood is too acidic, the excess hydrogen ions will be absorbed. If the blood is too basic, then the hydrogen ions will be released.

    49. Summary of Sections III, IV & V Acids donate a proton; bases accept it. The pH scale is related to the [H+]. Acids are pH 1-7; bases are pH 7-14 and neutral is pH 7. Buffers maintain pH within a narrow pH range. Summary of sections II, IV and V: Acids donate a proton and bases accept it. Acids have a pH of between 1 and 7 and bases have a pH of between 7 and 14. Neutral pH is pH 7. Buffers maintain pH within a narrow pH range.Summary of sections II, IV and V: Acids donate a proton and bases accept it. Acids have a pH of between 1 and 7 and bases have a pH of between 7 and 14. Neutral pH is pH 7. Buffers maintain pH within a narrow pH range.

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