What is the pH of a solution in which [H₃O⁺] = 1.2 × 10^-3 M? A)1.20 B)2.92 C)11.08 D)12.80 E)8.33 × 10^-12

Question

Quizplus · Accepted Answer

This question is asking for the pH of a solution based on a given concentration of ions. To solve for pH, we need to find the concentration of H+ ions in the solution. The given ions include HSO4-, which is a weak acid that can donate H+ ions in water. The dissociation equation is:
HSO4- + H2O ⇌ H3O+ + SO4 2-
The equilibrium expression for this equation is:
Ka = [H3O+][SO4 2-]/[HSO4-] = 1.2 × 10-3
Since the initial concentration of HSO4- is equal to the equilibrium concentration, we can assume that x = [H+] = [HSO4-] in the equilibrium expression. Therefore, we can rewrite the equation as:
Ka = x2/[HSO4-] = x2/1.2 × 10-3
Solving for x, we get:
x = 2.92 × 10-6 M
The pH is given by:
pH = -log[H+] = -log(2.92 × 10-6) = 5.54
Therefore, the correct answer is B) 2.92.

What Is the PH of a Solution in Which [H3O+]

What Is the PH of a Solution in Which [H₃O⁺]