Question

An industrial chemist studying bleaching and sterilizing prepares several hypochlorite buffers. Find the pH of 0.200 M HClO and 0.200 M NaClO. (Ka for HClO = 2.9 × 10−8)

Answer 1

Answer:

The pH is 7.54

Explanation:

The Henderson - Hasselbalch equation states that for a buffer solution which consists of a weak acid and its conjugate base, the buffer pH is given by:

pH $=pk_{a} +log(\frac{[conjugate base]}{[weakacid]})$

pkₐ is for the acid

In this case, the buffer hypochlorous acid  HClO is a weak acid, and its conjugate base is the hypochlorite anion ClO⁻  is delivered to the solution via sodium hypochlorite NaClO .

NaCIO = 0.200 M

HCIO = 0.200 M

pkₐ = -log₁₀ kₐ = -log₁₀ (2.9 × 10⁻⁸) = 7.54

∴pH = $=7.54 +log\frac{0.2}{0.2}$ = 7.54