Buffers

Question 1

What is a Buffer solution?

Answer 1

• a weak acid or a weak base AND
• the salt of the weak acid or weak base

Question 2

What does a buffer do?

Answer 2

Resists changes in pH when amounts of acid or base are added

Question 3

Buffer? KF/HF

Answer 3

• HF is weak Acid
• F- is conj base
  BUFFER

Question 4

Buffer? KBr/HBr

Answer 4

• Br- is base
• HBr is the strong conj. acid
  NOT A BUFFER

Question 5

Buffer? Na2CO3/NaHCO3

Answer 5

• CO3^2- is a base
• HCO3- is the conj acid
  BUFFER

Question 6

Buffer? CH3COOH/CH3COONa

Answer 6

• CH3COOH is an acid
• CH3COO- is its conj base
  BUFFER

Question 7

When [Hin]/[in] >/= 10 then…and why?

Answer 7

The acid color will predominate. Due to higher concentration of acid present.

Question 8

Buffer Capacity

Answer 8

Amount of acid or base a buffer system can absorb without significantly changing pH.

Question 9

Concentration of acid/base in a buffer solution

Answer 9

Must contain high acid-base conjugate concentrations. The higher the concentration = the higher buffer capacity

Question 11

When [Hin]/[in] </= 10 means… and why?

Answer 11

Conj Base color will predominate. Due to higher concentration of base present

Question 12

What influences Buffer Capacity? Why?

Answer 12

Higher [H+] and [OH-] result in greater buffer capacity.
- as conc. Increases this allows for more rxns between acid/conj base and added component to occur, resisting change in pH

Question 13

Buffer A is HA/A-
Whats happens when:
1. Add H+
2. Add OH-

Answer 13

1. Increase in HA and Decrease in A-
2. Increase in A- and Decrease in HA

Question 14

Buffer B HB+/B
What happens when:
1. Add H+
2. Add OH-

Answer 14

1. Increase in HB+ and Decrease in B
2. Increase in B and Decrease in HB