21 Buffers & Neutralisation

Question 1

What is a buffer solution?

Answer 1

A buffer solution is a system that minimises pH changes when small amounts of acid or a base are added.

Question 2

Which two components do buffer solutions contain?

Answer 2

• A weak acid (HA) which removes added alkali

- A conjugate base (A-) removes added acid

Question 3

What are the two methods for preparing a buffer?

Answer 3

1) Preparation from a weak acid and its salt
e. g. CH3COOH/CH3COONa
2) Excess of a weak acid and a strong alkali,
e. g. excess CH3COOH/NaOH

Question 4

When is a buffer most effective?

Answer 4

A buffer is most effective at removing either added acid or alkali when there are equal concentrations of the weak acid and its conjugate base.

Question 5

Why are buffer solutions necessary for the human body?

Answer 5

Human body relies on precise pH control where enzymes are particularly sensitive and each has an optimum pH.

Question 6

What pH should normal healthy blood be at?

Answer 6

7. 40

- The buffer solutions maintains it between 7.35-7.45

Question 7

Which buffer system plays an important role in human body?

Answer 7

• Carbonic acid-hydrogencarbonate buffer system

H2CO3/HCO3-

Question 8

What is the equivalence point?

Answer 8

The equivalence point of the titration is the volume of one solution that reacts exactly with the volume of the other solution.

Question 9

What happens at the end point of the titration?

Answer 9

• At the end point of a titration, the indicator contains equal concentrations of HA and A- .
• The colour will be in between the two extreme colours.