L4: pH & buffering

Question 1

What is pH?

Answer 1

Measure of H+ ion concentration

Question 2

What does acidity depend only on?

Answer 2

Free H+ ion

Question 3

How is acid-base balance regulated in the body?

Answer 3

lungs
kidneys
chemical buffers

Question 4

How does a doctor evaluate an acid-base balance?

Answer 4

Measure pH & levels of CO2 (acid) & bicarbonate (base) in the blood

Question 5

How do buffers resist abrupt & large swings in the pH of body fluids?

Answer 5

1) Release H+ (acids) when pH rise
2) Bind H+ (bases) when pH drops

Question 6

Acids & bases
(proton donors/acceptor)

Answer 6

Acids: Proton donors
Bases: Proton acceptors

Question 7

Define strong acids

Answer 7

acids that dissociate completely in solution

Question 8

Define weak acids

Answer 8

Acids that dissociate incompletely

Question 9

Define pKa

Answer 9

pKa = -logKa
pH when acid is half dissociated

Question 10

Henderson-Hasselbach equation

Answer 10

pH = pKa + log (A-)/(HA)
pH = pKa + log (conjugatebase)/(acid)

Question 11

What are buffers?

Answer 11

Mixtures of weak acids & their conjugate bases

Question 12

Define buffering

Answer 12

Ability of a solution to resist a change in pH when acid/alkali is added

Question 13

TRUE OR FALSE?

There are equal amounts of dissociated & non-dissociated forms of the acid at pKa

Answer 13

TRUE

Question 14

How can buffering resist a change in pH?

Answer 14

If H+ are added, they can be picked up by the conjugate base

If OH- are added, acid can donate a proton to form H2O

Resulting in no change to pH

Question 15

What is an important buffer in the blood?

Answer 15

Haemoglobin

Question 16

What makes haemoglobin a good blood buffer?

Answer 16

Presence of large no. of histidine residues