Titration Curves: Quiz
Seven questions on titration curves, equivalence points and indicators, with explanations.
Titration Curves: Quiz
7 questions
Strong acid + strong base gives a neutral salt (NaCl), so the equivalence point is at pH 7.00 (25 °C).
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Answer: 7.00
Strong acid + strong base gives a neutral salt (NaCl), so the equivalence point is at pH 7.00 (25 °C).
At equivalence the solution contains acetate, a weak base, so the pH is above 7 (8.72 for 0.100 M solutions).
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Answer: above 7
At equivalence the solution contains acetate, a weak base, so the pH is above 7 (8.72 for 0.100 M solutions).
Half the acid has been converted to its conjugate base, so [HA] = [A⁻] and pH = pKa + log(1) = pKa.
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Answer: the pKa of the acid
Half the acid has been converted to its conjugate base, so [HA] = [A⁻] and pH = pKa + log(1) = pKa.
Moles HCl = 0.100 × 0.02500 = 0.00250 mol; volume NaOH = 0.00250 ÷ 0.100 = 0.0250 L = 25.0 mL.
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Answer: 25.0 mL
Moles HCl = 0.100 × 0.02500 = 0.00250 mol; volume NaOH = 0.00250 ÷ 0.100 = 0.0250 L = 25.0 mL.
HCl left = 0.00250 − 0.00125 = 0.00125 mol in 37.50 mL: [H₃O⁺] = 0.0333 M, pH = 1.48. The answer 1.30 forgets that the volume has increased.
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Answer: 1.48
HCl left = 0.00250 − 0.00125 = 0.00125 mol in 37.50 mL: [H₃O⁺] = 0.0333 M, pH = 1.48. The answer 1.30 forgets that the volume has increased.
The equivalence point is at about pH 8.7, inside the steep jump where phenolphthalein changes colour. Methyl orange would change far too early.
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Answer: Phenolphthalein (pH 8.2–10.0)
The equivalence point is at about pH 8.7, inside the steep jump where phenolphthalein changes colour. Methyl orange would change far too early.
A weak acid releases fewer H₃O⁺ ions than a strong acid of the same concentration (pH 2.88 vs 1.00).
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Answer: Acetic acid ionizes only partly
A weak acid releases fewer H₃O⁺ ions than a strong acid of the same concentration (pH 2.88 vs 1.00).