Igcse Model Questions Vol1 2022 Chemistry Question 14

Practice objective / multiple choice question 14 from the 2022 Igcse Model Questions Vol1 Chemistry examination.

Igcse Model Questions Vol1 2022 Chemistry Objective / Multiple Choice Medium Difficulty
Question 14 IGCSE_MODEL_QUESTIONS_VOL1 • 2022 • CHEMISTRY • objective

A \(25.0\) cm³ sample of \(0.20\) M \(\mathrm{H_2SO_4}\) is diluted to \(250.0\) cm³ with water. (a) Calculate the pH of the diluted solution before any base is added, assuming the second dissociation constant of \(\mathrm{HSO_4^-}\) is \(K_a = 1.2\times10^{-2}\). (b) How many millilitres of \(0.10\) M NaOH are required to reach the equivalence point? (c) If phenolphthalein is used as the indicator, will it change colour at the equivalence point? Justify your answer.

Answer Options

A. (a) pH ≈ 1.30; (b) 90.0 mL; (c) Yes, because phenolphthalein changes colour in the pH range 8-10.
B. (a) pH ≈ 1.70; (b) 75.0 mL; (c) Yes, because the pH at equivalence is about 8, within phenolphthalein's range.
C. (a) pH ≈ 2.00; (b) 85.0 mL; (c) No, because the pH at equivalence is about 9, outside phenolphthalein's range.
Correct Answer D. (a) pH ≈ 1.49; (b) 80.0 mL; (c) No, because the pH at equivalence is about 7, outside phenolphthalein's range.
Correct Answer
D
Correct Option:
(a) pH ≈ 1.49; (b) 80.0 mL; (c) No, because the pH at equivalence is about 7, outside phenolphthalein's range.

About This Question

This is Igcse Model Questions Vol1 2022 Chemistry Question 14. It is one of the objective questions from the 2022 Igcse Model Questions Vol1 Chemistry examination.

Difficulty level: Medium .

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