Reactions of Acids Practice Questions

Question 1

3 marks

A student used universal indicator to test four solutions, A, B, C and D.

Table 1 shows the pH of each solution.

Solution	pH
A	1
B	5
C	7
D	13

(a)

Give the letter of the solution that is neutral.

/ 1

(b)

Give the colour of universal indicator in solution D.

/ 1

(c)

Name the ion that is produced by all acids in aqueous solution.

/ 1

Question 2

3 marks

Metals can react with dilute acids to produce a salt and a gas.

(a)

Complete the word equation for the reaction of magnesium with dilute sulfuric acid.

magnesium + sulfuric acid $\rightarrow$ ............................ + ............................

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(b)

Iron reacts with dilute hydrochloric acid. Name the salt produced.

/ 1

Question 3

3 marks

A student added small pieces of calcium carbonate to dilute nitric acid in a beaker. The mixture fizzed.

(a)

Name the salt produced in this reaction.

/ 1

(b)

Name the two other products of this reaction.

/ 1

(c)

The formula of the calcium ion is $\mathrm{Ca^{2+}}$ and the formula of the nitrate ion is $\mathrm{NO_3^-}$ .

Deduce the formula of the salt produced.

/ 1

Question 4

2 marks

Acids can be described as strong or weak, and as dilute or concentrated.

(a)

State what is meant by a weak acid.

/ 1

(b)

State what is meant by a concentrated acid.

/ 1

Question 0

4 marks

Zinc and iron both react with dilute acids.

(a)

Write a balanced symbol equation, including state symbols, for the reaction of zinc with dilute sulfuric acid.

/ 2

(b)

Iron reacts with dilute hydrochloric acid to produce iron(II) chloride and hydrogen.

Write a balanced symbol equation for this reaction.

/ 2

Question 0

4 marks

When magnesium reacts with dilute hydrochloric acid, the ionic equation for the reaction is:

$\mathrm{Mg(s) + 2H^+(aq) \rightarrow Mg^{2+}(aq) + H_2(g)}$

(a)

Write the half equation for the oxidation of magnesium in this reaction.

/ 1

(b)

Identify the species that is reduced in this reaction and explain your answer in terms of electrons.

/ 2

(c)

Explain why this reaction is described as a redox reaction.

/ 1

Question 0

9 marks

Copper(II) carbonate is an insoluble solid. A student is asked to prepare a pure, dry sample of copper(II) nitrate crystals from copper(II) carbonate and dilute nitric acid.

Part of the apparatus the student uses is shown below.

(a)

Name the piece of apparatus labelled A.

/ 1

(b)

Describe a method the student could use to prepare a pure, dry sample of copper(II) nitrate crystals, starting from dilute nitric acid and solid copper(II) carbonate.

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(c)

Suggest two reasons why the student should evaporate the salt solution using a water bath rather than heating it strongly with a Bunsen burner.

/ 2

Question 0

4 marks

A student carried out a titration to find the volume of $0.100\ \mathrm{mol/dm^3}$ hydrochloric acid needed to neutralise $25.0\ \mathrm{cm^3}$ of sodium hydroxide solution. The acid was placed in a burette.

(a)

Name the piece of apparatus the student should use to measure $25.0\ \mathrm{cm^3}$ of sodium hydroxide solution accurately into the conical flask.

/ 1

(b)

Before filling the burette, the student rinsed it with some of the hydrochloric acid.

Explain why.

/ 2

(c)

Explain why universal indicator should not be used in this titration.

/ 1

Question 0

4 marks

A student titrated $25.0\ \mathrm{cm^3}$ of potassium hydroxide solution with dilute nitric acid from a burette.

Table 2 shows the student's results.

	Titration 1	Titration 2	Titration 3	Titration 4
Final burette reading in $\mathrm{cm^3}$	25.40	24.80	25.20	24.85
Initial burette reading in $\mathrm{cm^3}$	0.00	0.00	0.30	0.00
Volume of acid added in $\mathrm{cm^3}$	25.40	24.80		24.85

(a)

Calculate the volume of acid added in titration 3.

Volume = .................................... $\mathrm{cm^3}$

/ 1

(b)

Give a reason why the result of titration 1 should not be used to calculate the mean titre.

/ 1

(c)

Calculate the mean titre using the concordant results.

Mean titre = .................................... $\mathrm{cm^3}$

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Question 0

4 marks

Dilute sulfuric acid is neutralised by potassium hydroxide solution.

(a)

Name the salt produced in this reaction.

/ 1

(b)

Write a balanced symbol equation for this reaction.

/ 2

(c)

Explain, in terms of ions, what happens when an acid is neutralised by an alkali.

/ 1

Question 0

3 marks

A student measured the pH of a solution of hydrochloric acid using a pH probe. The pH of the solution was 1.

The student then added distilled water to the acid. The pH of the diluted acid was 3.

(a)

Explain, in terms of ions, why adding water to the hydrochloric acid caused the pH to increase.

/ 2

(b)

Calculate the factor by which the hydrogen ion concentration decreased when the pH changed from 1 to 3.

/ 1

Question 0

5 marks

A student used a titration to find the concentration of a solution of dilute sulfuric acid.

$25.0\ \mathrm{cm^3}$ of $0.100\ \mathrm{mol/dm^3}$ sodium hydroxide solution was exactly neutralised by $22.50\ \mathrm{cm^3}$ of the dilute sulfuric acid.

The equation for the reaction is:

$\mathrm{H_2SO_4 + 2NaOH \rightarrow Na_2SO_4 + 2H_2O}$

(a)

Calculate the concentration of the sulfuric acid in $\mathrm{mol/dm^3}$ .

Give your answer to 3 significant figures.

Concentration = .................................... $\mathrm{mol/dm^3}$

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(b)

Calculate the concentration of the sulfuric acid in $\mathrm{g/dm^3}$ .

Relative formula mass ( $M_r$ ) of $\mathrm{H_2SO_4} = 98$

Concentration = .................................... $\mathrm{g/dm^3}$

/ 2

Question 0

4 marks

A student measured the pH of two acids. Both solutions had a concentration of $0.10\ \mathrm{mol/dm^3}$ .

Table 3

Acid	pH of $0.10\ \mathrm{mol/dm^3}$ solution
Hydrochloric acid	1
Ethanoic acid	3

(a)

Explain, in terms of ionisation, why the ethanoic acid solution has a higher pH than the hydrochloric acid solution.

/ 3

(b)

The student concluded: 'The ethanoic acid must be more dilute than the hydrochloric acid because its pH is higher.'

Explain why the student is not correct.

/ 1

Question 0

4 marks

Iron(III) oxide ( $\mathrm{Fe_2O_3}$ ) is an insoluble base. A student added iron(III) oxide to warm dilute nitric acid to make a solution of iron(III) nitrate.

The formula of the iron(III) ion is $\mathrm{Fe^{3+}}$ and the formula of the nitrate ion is $\mathrm{NO_3^-}$ .

(a)

Deduce the formula of iron(III) nitrate.

/ 1

(b)

Write a balanced symbol equation for the reaction of iron(III) oxide with dilute nitric acid.

/ 2

(c)

The student added the iron(III) oxide until it was in excess.

Explain why.

/ 1

Atomic Structure & the Periodic Table

Bonds, Structure & Properties of Matter

Quantitative Chemistry

Chemical Changes

Energy Changes

Chemical Change: Rate & Extent

Organic Chemistry

Chemical Analysis

Chemistry of the Atmosphere

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