Chemistry

Acid-base Equilibria — Multiple-Choice Questions (Edexcel IAL Chemistry): Exam Questions

Exam code:YCH11

10 questions · 15 marks · ≈ 15 min

Guided practice

13 marksmedium

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?

Choose your answer

0.1 mol dm^–3 CH₃COOH

1.0 mol dm^–3 CH₃COOH

0.1 mol dm^–3 HCl

1.0 mol dm^–3 HCl

(b)

Which basic solution was used in the titration?

Choose your answer

NH₃

LiOH

Ba(OH)₂

NaOH

(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.

Choose your answer

21 markmedium

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 pK_a = 6.33?

Use your Data Booklet.

Choose your answer

bromocresol green

bromothymol blue

litmus

phenolphthalein

31 markmedium

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 mark)

		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

41 markmedium

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

CH₃COOH + CH₂ClCOOH ⇌ CH₃COO $H_{2}^{+}$ + CH₂ClCOO⁻

The Brønsted-Lowry acids in this equilibrium are

Choose your answer

CH₃COOH and CH₂ClCOOH

CH₃COOH and CH₃COO $H_{2}^{+}$

CH₂ClCOOH and CH₃COO $H_{2}^{+}$

CH₃COO $H_{2}^{+}$ and CH₂ClCOO⁻

51 markmedium

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

[pK_w = 14]

Choose your answer

11.7

12.0

12.3

13.3

63 marksmedium

(a)

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) $\rightarrow$ 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?

Choose your answer

region T

region U

region V

region W

(b)

Which of these is the best indicator to use in this titration?

[Refer to the Data Booklet]

Choose your answer

methyl red

phenol red

phenolphthalein

thymol blue

(c)

What is the approximate pH of an ammonium chloride solution?

Choose your answer

2.0

5.8

9.7

11.3

71 markmedium

A racemic mixture of a chiral compound shows no net rotation of plane-polarised light.

Which of these is the reason?

Choose your answer

The mixture contains unequal amounts of each enantiomer

The molecules in the mixture do not contain a chiral centre

The two enantiomers rotate plane-polarised light by equal amounts in opposite directions, which cancel out

The two enantiomers rotate plane-polarised light in the same direction, which cancels out

81 markmedium

Which of these processes is always exothermic?

Choose your answer

First electron affinity

First ionisation energy

Standard enthalpy change of atomisation

Standard enthalpy change of vaporisation

91 markmedium

The high-resolution ¹H NMR spectrum of a compound with molecular formula C₄H₈O₂ is shown.

NMR spectrum with peaks at chemical shifts 0-11 ppm; major peaks at 1-3 ppm. X-axis labelled as chemical shift, δ/ppm.

Which compound corresponds to this spectrum?

Choose your answer

butanoic acid

ethyl ethanoate

ethyl methanoate

methyl propanoate

102 markshard

(a)

This question is about weak acids.

pK_a of ethanoic acid, CH₃COOH = 4.8

pK_a of chloroethanoic acid, CH₂ClCOOH = 2.9

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

Choose your answer

0.27

1.95

2.90

3.90

(b)

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

		Acid	Conjugate base
☐	A	$\mathrm{CH}_{3}\mathrm{COOH}$	$\mathrm{CH}_{3}\mathrm{COO}^{-}$
☐	B	$\mathrm{CH}_{3}\mathrm{COOH}$	$\mathrm{CH}_{3}\mathrm{COOH}_{2}^{+}$
☐	C	$\mathrm{CH}_{2}\mathrm{ClCOOH}$	$\mathrm{CH}_{2}\mathrm{ClCOO}^{-}$
☐	D	$\mathrm{CH}_{2}\mathrm{ClCOOH}$	$\mathrm{CH}_{2}\mathrm{ClCOOH}_{2}^{+}$

Choose your answer

Enthalpy change of dissociation of water

Concentration of hydrogen ions

☐

endothermic

higher at 100°C than at 25°C

☐

endothermic

lower at 100°C than at 25°C

☐

exothermic

higher at 100°C than at 25°C

☐

exothermic

lower at 100°C than at 25°C

Acid

Conjugate base

☐

\mathrm{CH}_{3}\mathrm{COOH}

\mathrm{CH}_{3}\mathrm{COO}^{-}

☐

\mathrm{CH}_{3}\mathrm{COOH}

\mathrm{CH}_{3}\mathrm{COOH}_{2}^{+}

☐

\mathrm{CH}_{2}\mathrm{ClCOOH}

\mathrm{CH}_{2}\mathrm{ClCOO}^{-}

☐

\mathrm{CH}_{2}\mathrm{ClCOOH}

\mathrm{CH}_{2}\mathrm{ClCOOH}_{2}^{+}