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Chemistry · Ionic equilibrium: Weak and strong electrolytes, ionization of electrolytes

Calculate the ratio of and in a mixture of HCOOH \) and \)

Calculate the ratio of \( H C O O^{-} \) and \( F^{-} \) in a mixture of \( 0.2 M \) HCOOH \( \left(K_{a}=\right. \) \( \left.2 \times 10^{-4}\right) \) and \( 0.1 M H F\left(K_{a}=6.6 \times\right. \) \( \left.10^{-4}\right) \)

  • A. 1: 6.6
  • B. 1: 3.3
  • C. 2: 3.3
  • D. 3.3 : 2

Step-by-step solution

The ratio [HCOO-]/[F-] is derived from the acid dissociation constants and initial concentrations: [HCOO-]/[F-] = (Ka_HCOOH × [HCOOH])/(Ka_HF × [HF]) = (2×10⁻⁴ × 0.2)/(6.6×10⁻⁴ × 0.1) = 4×10⁻⁵ / 6.6×10⁻⁵ = 40/66 = 20/33 ≈ 0.606. This corresponds to a ratio of 20:33, which simplifies approximately to 2:3.3.
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