Question

Determine the pH when 5.89 g of sodium acetate (NaOOCCH3) is dissolved in 190 mL of water. Ka of acetic acid is 1.8 10-5

Answer 1

Answer on Question #63570 - Chemistry – Inorganic Chemistry

Determine the pH when 5.89 g of sodium acetate (NaOOCCH₃) is dissolved in 190 mL of water. Kₐ of acetic acid is 1.8·10⁻⁵.

Solution.

NaOOCCH₃ ↔ Na⁺ + CH₃COO⁻

CH₃COO⁻ + H₂O → CH₃COOH + OH⁻

Kₐ = 1.8·10⁻⁵; pKₐ = -lgKₐ = 4.74

$$pH = 7 + \frac{1}{2} pK_{CH_3COOH} + \frac{1}{2} \lg C_{NaOOCCH_3}$$

C(NaOOCCH₃) = ν(NaOOCCH₃)/V(solution) = m(NaOOCCH₃)/(M(NaOOCCH₃) × V(solution)) = 5.89/((23+32+24+3) × 0.19) = 0.378 mol/L

pH = 7 + 1/2 × 4.74 + 1/2 × lg(0.378) = 9.16

Answer: pH = 9.16

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