Question

If you mix equal volumes of 0.1M NaOH with 0.2M acetic acid, is the resulting solution a buffer? Why or why not? Given that the pKa of acetic acid is 4.76, what is the pH of the resulting solution?

Answer 1

Hello, please find the answer in the attachment below.

pH=pKa

A buffer solution is that solution which resists any change in its pH value on dilution or on addition of a small amount of a strong acid or a strong alkali.

Types of buffer:

(1) Acidic buffer

(2) Basic buffer

Acidic buffer: These are normally prepared by mixing either equal or different volumes of similar solutions of a weak acid and it's salt.

Ex: (CH₃COOH+CH₃COONa)

Basic buffer: These buffer solutions are prepared generally, by mixing either equal or different volumes of equimolar solutions of a weak base and it's salt.

Ex: ( NH₄OH+NH₄Cl)

The pH of an acid or base buffer solution can be calculated by the use of Henderson's equation I.e.

Acidic buffer is prepared by the reaction of weak acid and strong base which gives a salt of weak acid as product.

Basic buffer is prepared by tge reaction of weak base and strong acid which gives a salt of weak base as product.

pH=pKa+ log[salt/acid] => for acidic buffer

pOH=pKb+log[salt/base] => for basic buffer.

In the question the reaction of NaOH and CH₃COOH gives CH₃COONa a salt of weak acid, hence the reaction is acidic buffer.

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