Question

What is [H₃O⁺] in a solution of 0.075 M HNO₂ and 0.030 M NaNO₂?

a) 1.8 × 10⁻⁵ M
b) 1.5 × 10⁻⁴ M
c) 2.5 × 10⁻⁴ M
d) 3.0 × 10⁻³ M

Answer 1

To find the concentration of [H₃O⁺] in the given solution, we can consider the dissociation of HNO₂ and use the equilibrium constant expression. The Ka value for HNO₂ is 1.8 × 10⁻⁵ M.

Step-by-step explanation:

The question asks for the concentration of [H₃O⁺] in a solution of 0.075 M HNO₂ and 0.030 M NaNO₂. To find this, we first need to consider the dissociation of HNO₂.

HNO₂ can act as a weak acid and can release H₃O⁺ ions. The equation for its dissociation is:

HNO₂(aq) ⟶ H⁺(aq) + NO₂⁻(aq)

The equilibrium constant expression for this dissociation is Ka = [H⁺][NO₂⁻]/[HNO₂]. Using the given concentrations of HNO₂ and NaNO₂, we can calculate the concentration of [H₃O⁺] using the Ka value for HNO₂, which is 1.8 × 10⁻⁵ M.