14B.2

Question 1

what is a buffer solution

Answer 1

a solution that minimizes the change in pH when small amounts of either acid or base

Question 2

what are the two ways to make buffer solutions

Answer 2

1. add a weak base and its conjugate acid
2. add a weak acid and its conjugate base

Question 3

what is an example of weak acid and its conjugate base

Answer 3

ethanoic acid and sodium ethanoate

Question 4

the salt of a weak acid has to be

Answer 4

soluble in water

Question 5

weak acid and its conjugate base forms a pH of

Answer 5

less than 7

Question 6

in buffer solution pH calculations saying that the extend of acid dissociation is negligible tells us that

Answer 6

1. the acid concentration at eq will be half the starting concentration
2. the bass of the acid will be considered to be made up from the acid salt so at eq it will have half the starting concentration (same as the acid)

Question 7

why do we use half the concentration of the acid and the salt in Buffer solution pH calculations

Answer 7

because equal volumes of each solutions were mixed, so the total volume of the mixture is twice the volume of each

Question 8

when adding a little base to a buffer solution what will happen

Answer 8

the Oh ions would react with the acid to form a base and H2O

Question 9

when adding a little acid to a buffer solution what will happen

Answer 9

H ions would react with the base to form a weak acid

Question 10

why is there a minimal effect on pH when adding small amounts of acid and base in buffer solutions

Answer 10

because the extent of acid dissociation is ignored we will have a large amounts of acid, and because the full dissociation of the salt we would have large amount of the conjugate base, therefore any addition of small amounts of acid and base will barely effect the acid and its base since they have large values of concentration so the effects are negligible. so the equation of [H] ions is given by Ka x acid/base so the Ka remains constant at a set temp, and the ratio of acid/base also remains fairly constant since they come at large values making the acid/base ratio fairly constant so the value of the [H] remains constant

Question 11

when adding a 0.01 mol of H+ ions what will happen to the concentration of acid and its conjugate base

Answer 11

since the H ions would react with the base to form the acid and its a 1:1 ratio the new con of the acid would be 0.01 increase, and the con of the base would be 0.01 decrease

Question 12

the concentration of a base would be the same as its salt if

Answer 12

sodium or potassium salt is used

Question 13

what is the Henderson-Hasselbalch equation

Answer 13

pH = pKa + salt or base/acid (derivation page 97)

Question 14

what is an example of weak base and its conjugate acid buffer solution

Answer 14

ammonia and ammonium ion which is usually supplied in the form of ammonium chloride

Question 15

what is the pH of a buffer solution made from weak base and its conjugate acid

Answer 15

greater then 7

Question 16

what is the buffer action for weak base and its conjugate acid

Answer 16

the dissociation of the acid provides large amounts of the acid and the base so with relatively large amounts of base acid and the base there change when adding a [H] OR [OH] ions would negligible so pH = pKa + base/acid with pKa being constant at a set temp and the base/acid ratio being fairly constant the pH would remain constant

Question 17

how to make buffer solutions

Answer 17

page 98

Question 18

what is the Ka of ethanoic acid dissociation

Answer 18

1.74 x 10^-5

Question 19

what is the Ka of ammonium dissociation

Answer 19

5.62 x 10^-10

Question 20

why are buffer solutions important in our bodies

Answer 20

because enzymes work best in certain conditions and having buffer solutions provide small changes of pH keeping thoose conditions

Question 21

what is the most important buffer solution in the body

Answer 21

carbonic acid and its conjugate base which is hydrogen carbonate

Question 22

why is the carbonic acid and hydrogen carbonate the most important buffer in the body

Answer 22

it is coupled with the respiratory system of the body

Question 23

how does the body maintain its pH in the carbonic acid and hydrogen carbonate buffer solution

Answer 23

for loss of H - sometimes when people diuretics the body excretes large amounts of urine that can contain acid, so when acid is lost the eq shifts to the right making more carbonic acid ionize to form H+ returning the pH to normal
for gain of H - when the body gains acid maybe through lactic acid the eq would shift to the left forming more carbonic acid which would then breakdown into CO2 which will be removed more the body through breathing restoring the the pH back to its original value

Question 24

what is the problem with carbonic acid

Answer 24

it unstable and can break down to from CO2(aq) and H2O(aq)

Question 25

what is the equation for carbonic acid dissociation and the ratio of it and its base

Answer 25

its base is 20 times more than it as it fits what the body needs equation page 98

Question 26

the spoilage of food by microorganisms depends mostly one

Answer 26

the pH of the food

Question 27

what is a buffer capacity

Answer 27

the measure of the amount of acid/base require to significantly change the pH of a food or a solution of an acid or base

Question 28

why does proteins have a higher buffer capacity

Answer 28

because the amino acid has both acidic and basic properties so 3ani buffer solution is formed in proteins

Question 29

why does a higher buffer capacity effect the spoilage of food

Answer 29

because with a higher buffer capacity the more time needed for the pH of the food to change to allow the bacteria to multiply

Question 30

buffer solution in food is good because

Answer 30

higher buffer capacity therefore lesser chance of spoilage