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

The pH is 7.54

Step-by-step 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(([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(0.2)/(0.2)` = 7.54