Question

H3PO4 (aq) + H2O (l) ⇔ H2PO4- (aq) + H3O+ (aq) Ka = 7.1 x 10-3

A buffer was prepared using 0.00650 M H3PO4 and 0.0125 M NaH2PO4. Calculate the pH of the buffer solution.

Answer 1

The pH of the buffer solution : 2.433

Further explanation

A buffer solution is a solution that can maintain a good pH value due to the addition of a little acid or a little base or dilution.

The buffer solution can be acidic or basic

Acid buffer solution consists of weak acids (H₃PO₄) and their salts(NaH₂PO₄)

`\tt [H^+]=Ka*([\:weak\:acid])/([salt]* valence)`

valence according to the amount of salt anion

[H₃PO₄]=0.00650 M

[NaH₂PO₄]=0.0125 M

`\tt [H^+]=7.1.10^(-3)(0.0065)/(0.0125)\\\\(H^+]=3.692.10^(-3)\\\\pH=-log[H^+]\\\\pH=3-log3.692\\\\pH=2.433`