Question

Determine the pH of each of the following solutions.

Part A

0.11 molL−1 NH4Cl

Express your answer to two decimal places.

Part B

0.15 molL−1 CH3COONa

Express your answer to two decimal places.

Part C

0.13 molL−1 NaCl

Express your answer to two decimal places.

Answer 1

part A)

NH4Cl is salt of weak base and strong acid

for such salts

pOH = 1/2 [pKw + pKb + log C]

pKb of NH3 = 4.74

pOH = 1/2 [14 + 4.74 + log 0.11]

pOH = 8.89

pH = 14 - 8.89

pH = 5.11

part B) CH3COONa is salt of weak acid and strong base

for such salts

pH = 1/2 [pKw + pKa + logC]

pKa of CH3COOH = 4.74

pH = 1/2 [14 + 4.74 + log 0.15]

pH = 8.96

part C) NaCl is salt of strong acid and strong base

for such salts pH is always neutral

pH = 7.00