Question

Hclo is a weak acid (ka=4.0x10^-8) and so the salt naclo acts as a weak base. what is the ph of a solution that is 0.037 m in naclo at 25 c

Answer 1

Given:

Concentration of NaClO = 0.037 M

ka (HClO) = 4.0*10⁻⁸

To determine:

The pH of the NaClO solution

Explanation:

The hydrolysis of the weak base can be represented by the ICE table shown below-

                ClO-      +     H2O    ↔    HClO    +       OH-

Initial        0.037M                              0                    0

Change         -x                                 +x                  +x

Equilibrium  (0.037-x)                        x                     x

kb  = kw/ka =  [HClO][OH-]/[ClO-]

10⁻¹⁴/4*10⁻⁸ = x²/(0.037-x)

x = [OH-] = 9.62*10⁻⁵

p[OH-] = -log[OH-] = -log [9.62*10⁻⁵] = 4.02

pH = 14-p[OH-] = 14 - 4.02 = 9.98

Ans: pH of the solution is 9.98