40 mL of 0.1 M ammonia solution is mixed with 20 mL of 0.1 M HCl.

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40 mL of 0.1 M ammonia solution is mixed with 20 mL of 0.1 M HCl. What is the pH of the mixture? ( pKb of ammonia solution is 4.74)

Options

(a) 4.74
(b) 2.26
(c) 9.26
(d) 5

Correct Answer:

9.26

Explanation:

40mL of 0.1 M ammonia solution = 40×0.1
= 4 milli equivalent ammonia solution,
20 mL of 0.1 M HCl = 20×0.1,
= 2 milliequivalent of HCl,
NH₄OH + HCl → NH₄Cl + H₂O. Initial milli.eqv. 4 2 0. Milli-eqv.after 4-2 0 2 reaction = 2. Therefore pOH = pK(b) + log[NH₄Cl]/NH₄OH] = 4.74 + log2/2
= 4.74 + log 1 = 4.74.
Therefore pH = 14 – 4.74 = 9.26.

Related Questions:

1. Which of the following on addition of water in presence of acid gives a ketone
2. Which among the following has the largest dipole moment
3. Acetic acid is weak acid than sulphuric acid because
4. Which of the following polymers is hard
5. Aniline reacts with which of these to form Schiff base

Topics: Equilibrium (104)
Subject: Chemistry (2512)

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