Edexcel International A Level Chemistry

Topic Questions

International A LevelChemistryEdexcelTopic Questions4: Rates, Equilibria and Further Organic Chemistry4.5 Acid-base Equilibria

4.5 Acid-base Equilibria

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1a1 mark

A graph of pH against volume of acid added for an acid-base titration is shown.

q4-paper-4-2021-june-edexcel-ial-chemistry

a)
Which acidic solution was used in the titration?

  • 0.1 mol dm–3 CH3COOH

  • 1.0 mol dm–3 CH3COOH

  • 0.1 mol dm–3 HCl

  • 1.0 mol dm–3 HCl

Choose your answer

1b1 mark
b)
Which basic solution was used in the titration?

  • NH3

  • LiOH

  • Ba(OH)2

  • NaOH

Choose your answer

1c1 mark
c)
A student suggested five indicators that might be used in this titration:

thymol blue
methyl orange
bromophenol blue
bromocresol green
phenolphthalein

How many of these indicators would be suitable? Use your Data Booklet.

  • 5

  • 4

  • 3

  • 2

Choose your answer

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21 mark

An example of a diprotic acid is cis-butenedioic acid. Titration of this acid using sodium hydroxide solution gave the titration curve shown.

gjjyyv5~_q5

Which indicator would be most suitable for measuring the end-point of the neutralisation of the proton in cis-butenedioic acid which has a pKa = 6.33?

Use your Data Booklet.

  • bromocresol green

  • bromothymol blue

  • litmus

  • phenolphthalein

Choose your answer

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31 mark

At 25°C, the pH of pure water is 7.00 and at 100°C, the pH of pure water is 6.14.
What can be deduced from this information?

(1)

      Enthalpy change of
dissociation of water		 Concentration of hydrogen ions
  ☐ A endothermic higher at 100°C than at 25°C
  ☐ B endothermic lower at 100°C than at 25°C
  ☐ C exothermic higher at 100°C than at 25°C
  ☐ D exothermic lower at 100°C than at 25°C

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41 mark

When ethanoic acid and chloroethanoic acid are mixed, an equilibrium is set up.

CH3COOH + CH2ClCOOH ⇌ CH3COOstraight H subscript 2 superscript plus+ CH2ClCOO−

The Brønsted-Lowry acids in this equilibrium are

  • CH3COOH and CH2ClCOOH

  • CH3COOH and CH3COObegin mathsize 16px style H subscript 2 to the power of plus sign end style

  • CH2ClCOOH and CH3COOstraight H subscript 2 superscript plus

  • CH3COOstraight H subscript 2 superscript plusand CH2ClCOO−

Choose your answer

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5
Sme Calculator1 mark

What is the pH of 0.010 mol dm−3 aqueous calcium hydroxide, Ca(OH)2 (aq)?

[pKw = 14]

  • 11.7

  • 12.0   

  • 12.3

  • 13.3

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6a1 mark

A titration was carried out by adding 0.1 mol dm−3 hydrochloric acid to
0.1 mol dm−3 aqueous ammonia.

HCl (aq) + NH3 (aq) rightwards arrow NH4Cl (aq)

The titration curve is shown.

q10-paper-4-jan-2021-edexcel-ial-chemistry

a)
Which region of the graph represents the most effective buffer solution?

  • region T

  • region U

  • region V

  • region W

Choose your answer

6b1 mark
b)
Which of these is the best indicator to use in this titration?

[Refer to the Data Booklet]

  • methyl red

  • phenol red

  • phenolphthalein

  • thymol blue

Choose your answer

6c1 mark
c)
What is the approximate pH of an ammonium chloride solution?

  • 2.0

  • 5.8

  • 9.7

  • 11.3

Choose your answer

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