Determine the pH of a 0.62 mol L^-1 NH₄NO₃ solution at 25 °C. The K_b for NH₃ is 1.76 × 10^-5. A) 2.48 B) 9.27 C) 11.52 D) 4.73 E) 9.45

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Quizplus · Accepted Answer

NH₄NO₃ is a salt of a weak base (NH₃) and a strong acid (HNO₃). In solution, NH₄⁺ acts as a weak acid. Using Kb for NH₃, we can find Ka for NH₄⁺: Ka = Kw/Kb = 1.0 × 10⁻¹⁴ / 1.76 × 10⁻⁵ = 5.68 × 10⁻¹⁰. Using the formula for weak acid dissociation, [H⁺] = √(Ka × C), where C is the concentration of NH₄⁺, we find [H⁺] = √(5.68 × 10⁻¹⁰ × 0.62) = 5.92 × 10⁻⁶. Thus, pH = -log[H⁺] = 4.73.

Determine the PH of a 0