Neco Model Questions Vol1 2025 Chemistry Question 9

Practice objective / multiple choice question 9 from the 2025 Neco Model Questions Vol1 Chemistry examination.

Neco Model Questions Vol1 2025 Chemistry Objective / Multiple Choice Hard Difficulty
Question 9 NECO_MODEL_QUESTIONS_VOL1 • 2025 • CHEMISTRY • objective

A 0.025 M solution of an unknown monoprotic weak acid HA (a carboxylic acid) is titrated with 0.10 M NaOH. At the half‑equivalence point the measured pH is 4.75.\n(a) Determine the pK_a of HA.\n(b) Given that the molecular formula of HA is C₃H₆O₂, identify the acid.\n(c) Calculate the pH of a 0.10 M solution of this acid at 25 °C.

Answer Options

A. pK_a = 5.00; acid = propanoic acid; pH of 0.10 M solution ≈ 2.88
B. pK_a = 4.75; acid = butanoic acid; pH of 0.10 M solution ≈ 2.70
C. pK_a = 4.75; acid = propanoic acid; pH of 0.10 M solution ≈ 3.10
Correct Answer D. pK_a = 4.75; acid = propanoic acid; pH of 0.10 M solution ≈ 2.88
Correct Answer
D
Correct Option:
pK_a = 4.75; acid = propanoic acid; pH of 0.10 M solution ≈ 2.88

About This Question

This is Neco Model Questions Vol1 2025 Chemistry Question 9. It is one of the objective questions from the 2025 Neco Model Questions Vol1 Chemistry examination.

Difficulty level: Hard .

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