Waec Model Questions Vol1 2018 Chemistry Question 45

Practice objective / multiple choice question 45 from the 2018 Waec Model Questions Vol1 Chemistry examination.

Waec Model Questions Vol1 2018 Chemistry Objective / Multiple Choice Hard Difficulty
Question 45 WAEC_MODEL_QUESTIONS_VOL1 • 2018 • CHEMISTRY • objective

A 0.250 M solution of benzoic acid (C₆H₅COOH) is partially neutralised by 0.015 mol of NaOH in a 200 mL flask, giving a buffer. The measured pH of the buffer is 3.80. Using this data, calculate the experimental acid dissociation constant (Ka) of benzoic acid and the percentage error relative to the literature value Ka = 6.3 × 10⁻⁵.

Answer Options

A. Ka = 7.5×10⁻⁵; % error ≈ 19 %
B. Ka = 5.2×10⁻⁵; % error ≈ 18 %
Correct Answer C. Ka = 6.8×10⁻⁵; % error ≈ 8 %
D. Ka = 6.0×10⁻⁵; % error ≈ 5 %
Correct Answer
C
Correct Option:
Ka = 6.8×10⁻⁵; % error ≈ 8 %

About This Question

This is Waec Model Questions Vol1 2018 Chemistry Question 45. It is one of the objective questions from the 2018 Waec Model Questions Vol1 Chemistry examination.

Difficulty level: Hard .

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