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Ionic equilibria and pH
5 NET Chemistry questions with answers and explanations.
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Adding sodium chloride to a saturated solution of silver chloride will make the silver chloride:
- 1 More soluble
- 2 Less soluble
- 3 Unaffected
- 4 Turn into a gas
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Correct answer: Less soluble
This is the common ion effect. Extra chloride ions push the equilibrium towards the solid.
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A buffer contains equal concentrations of acetic acid and acetate ion. The pKa of acetic acid is 4.76. What is the pH?
- 1 7.00
- 2 4.76
- 3 9.52
- 4 2.38
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Correct answer: 4.76
When [A-] = [HA], the log term is zero and pH = pKa = 4.76.
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What is the pH of 0.05 M sulphuric acid, taking both protons as fully ionised?
- 1 1.3
- 2 1
- 3 2
- 4 0.05
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What is the value of the ionic product of water, Kw, at 25 degrees C?
- 1 1 x 10^-7
- 2 1 x 10^-14
- 3 1 x 10^14
- 4 1 x 10^-1
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Correct answer: 1 x 10^-14
Kw = [H+][OH-] = 10^-7 x 10^-7 = 10^-14 at 25 degrees C.
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An aqueous solution of ammonium chloride is:
- 1 Acidic
- 2 Basic
- 3 Neutral
- 4 Strongly basic
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Correct answer: Acidic
It is a salt of a strong acid and a weak base. The ammonium ion releases protons in water.