CMB1004/L22 Acids, Bases & Buffers

Question 1

What do water molecules dissociate into?

Answer 1

H3O+ and OH-

Question 2

What is the equation for equilibrium constant of water?

Answer 2

Kw = [H+][OH-]

Question 3

What is the equation for pH?

Answer 3

pH = -log10[H+]

Question 4

Give 2 ways of preparing a buffer.

Answer 4

Large volume of weak acid with conjugate base
Large volume of weak base with conjugate acid

Question 5

At what point do buffers stabilise their pH?

Answer 5

Near their pKa

Question 6

What is the equilibrium constant of a weak acid or base called?

Answer 6

Acid dissociation constant

Question 7

What is the equation for pKa?

Answer 7

pKa = -log10(Ka)

Question 8

What would a liquid with a pKa of <3 be classed as?

Answer 8

Strong acid

Question 9

What would a liquid with a pKa of 3-7 be classed as?

Answer 9

Weak acid

Question 10

What would a liquid with a pKa of 7-11 be classed as?

Answer 10

Weak base

Question 11

What would a liquid with a pKa of >11 be classed as?

Answer 11

Strong base

Question 12

What is the equation for Ka for a generic HA <-> H+ + A- equation?

Answer 12

Ka = [H+][A-]/[HA]

Question 13

What is the Henderson Hasselbach equation?

Answer 13

pH = pKa + log([A-]/[HA])

Question 14

What 2 substances does blood use to maintain pH?

Answer 14

Carbonic acid
Hydrogen carbonate

Question 15

What is implied about a liquid is its pH is lower than pKa?

Answer 15

Molecule is mainly in weak acid form HA

Question 16

What is implied about the liquid if its pH is higher than pKa?

Answer 16

Molecule is mainly in conjugate base form A-

Question 17

What is implied about the liquid if pH = pKa?

Answer 17

Molecule is half dissociated

Question 18

What happens to amino acids as pH increases?

Answer 18

Charge decreases as more H+ ions disassociate

Question 19

What form do amino acids hold at neutral pH?

Answer 19

Zwitterionic form