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International A LevelChemistryEdexcelExam Questions4: Rates, Equilibria & Further Organic ChemistryAcid-base Equilibria

Acid-base Equilibria (Edexcel International A Level Chemistry): Exam Questions

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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

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

Which basic solution was used in the titration?

  • NH3

  • LiOH

  • Ba(OH)2

  • NaOH

Choose your answer

1c1 mark

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

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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

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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

    Choose your answer

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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 Calculator    1 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

    Choose your answer

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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

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

    • region T

    • region U

    • region V

    • region W

    Choose your answer

    6b1 mark

    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

    What is the approximate pH of an ammonium chloride solution?

    • 2.0

    • 5.8

    • 9.7

    • 11.3

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    1a
    Sme Calculator    1 mark

    This question is about weak acids.

    pKa of ethanoic acid, CH3COOH = 4.8

    pKa of chloroethanoic acid, CH2ClCOOH = 2.9

    What is the pH of a 0.100 mol dm−3 solution of chloroethanoic acid?

    • 0.27

    • 1.95

    • 2.90

    • 3.90

    Choose your answer

    1b
    Sme Calculator    1 mark

    Which is the acid-conjugate base pair in the reaction between ethanoic acid and chloroethanoic acid?

     

     

    Acid

    Conjugate base

    ☐

    A

    CH subscript 3 COOH

    CH subscript 3 COO to the power of minus

    ☐

    B

    CH subscript 3 COOH

    CH subscript 3 COOH subscript 2 superscript plus

    ☐

    C

    CH subscript 2 ClCOOH

    CH subscript 2 ClCOO to the power of minus

    ☐

    D

    CH subscript 2 ClCOOH

    CH subscript 2 ClCOOH subscript 2 superscript plus

      Choose your answer

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