Neco Model Questions Vol1 2025 Chemistry Question 10

Practice objective / multiple choice question 10 from the 2025 Neco Model Questions Vol1 Chemistry examination.

Neco Model Questions Vol1 2025 Chemistry Objective / Multiple Choice Medium Difficulty
Question 10 NECO_MODEL_QUESTIONS_VOL1 • 2025 • CHEMISTRY • objective

A buffer is prepared by dissolving 0.20 mol of acetic acid (CH₃COOH, K_a = 1.8 × 10⁻⁵) and 0.15 mol of sodium acetate (CH₃COONa) in 1.00 L of water.\n(a) Calculate the initial pH of the buffer.\n(b) After adding 0.050 mol of HCl, calculate the new pH.\n(c) How many moles of NaOH must be added to restore the pH to its original value?

Answer Options

Correct Answer A. Initial pH = 4.62; after HCl pH = 4.34; NaOH needed ≈ 0.051 mol
B. Initial pH = 4.50; after HCl pH = 4.25; NaOH needed ≈ 0.040 mol
C. Initial pH = 4.55; after HCl pH = 4.30; NaOH needed ≈ 0.060 mol
D. Initial pH = 4.70; after HCl pH = 4.20; NaOH needed ≈ 0.045 mol
Correct Answer
A
Correct Option:
Initial pH = 4.62; after HCl pH = 4.34; NaOH needed ≈ 0.051 mol

About This Question

This is Neco Model Questions Vol1 2025 Chemistry Question 10. It is one of the objective questions from the 2025 Neco Model Questions Vol1 Chemistry examination.

Difficulty level: Medium .

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