Final answer:
The pH of a 0.45 M solution of NaCN is 13.65.
Step-by-step explanation:
The pH of a solution can be calculated using the formula:
pH = -log[H+]
Given that NaCN is a salt of a weak acid (HCN), it will undergo hydrolysis in water:
HCN + H2O ↔ H3O+ + CN-
The equilibrium can be represented by the expression:
Ka = [H3O+][CN-] / [HCN]
Since NaCN is a strong electrolyte, it will fully dissociate into Na+ and CN- ions:
NaCN → Na+ + CN-
This means that the concentration of CN- ions will be equal to the concentration of NaCN. Therefore, the pH of a 0.45 M NaCN solution will depend on the dissociation of CN- ions:
NaCN → Na+ + CN-
[CN-] = 0.45 M
pOH = -log[CN-] = -log(0.45) = 0.35
pH = 14 - pOH = 14 - 0.35 = 13.65.