CAIE IGCSE Chemistry 7.3 Preparation of Salts Topic Practice

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Covered syllabus points

7.3.1—Preparation, separation and7.3.2—Salt solubility rules: soluble7.3.3—Hydrated substance as a substance that7.3.4—Preparation of insoluble salts by7.3.5—Term water of crystallisation as the

Question 1

[Maximum number: 1]

This question is about metals.

Zinc oxide neutralises both acids and bases.

Name the zinc compound that forms when zinc oxide neutralises dilute sulfuric acid.

Question 2

[Maximum number: 1]

The equation for the reaction between barium chloride and dilute sulfuric acid is shown.

BaCl2+H2SO4→BaSO4+2HCl\mathrm{BaCl}_{2}+\mathrm{H}_{2} \mathrm{SO}_{4} \rightarrow \mathrm{BaSO}_{4}+2 \mathrm{HCl}

Which row shows the state symbols for this equation?

BaCl2\mathrm{BaCl}_{2}

H2SO4\mathrm{H}_{2} \mathrm{SO}_{4}

BaSO4\mathrm{BaSO}_{4}

2 HCl

(aq)(\mathrm{aq})

(aq)(\mathrm{aq})

(s)(\mathrm{s})

(aq)(\mathrm{aq})

(aq)(\mathrm{aq})

(I)(\mathrm{I})

(s)(\mathrm{s})

(aq)(\mathrm{aq})

(I)(\mathrm{I})

(aq)(\mathrm{aq})

(s)(\mathrm{s})

(I)(\mathrm{I})

(aq)(\mathrm{aq})

(I)(\mathrm{I})

(aq)(\mathrm{aq})

(I)(\mathrm{I})

Question 3

[Maximum number: 6]

This question is about sulfuric acid and salts that are made from sulfuric acid.

Question (a)

(a)

Zinc reacts with dilute sulfuric acid. Aqueous zinc sulfate is one of the products.

Powdered zinc is added to dilute sulfuric acid. The mixture is stirred. More zinc is added, with stirring, until the zinc is in excess.

Zn( s)+H2SO4(aq)→ZnSO4(aq)+H2( g)\mathrm{Zn}(\mathrm{~s})+\mathrm{H}_{2} \mathrm{SO}_{4}(\mathrm{aq}) \rightarrow \mathrm{ZnSO}_{4}(\mathrm{aq})+\mathrm{H}_{2}(\mathrm{~g})

The mixture is then filtered.

[ 5 ]

Question (i)

(i)

State two observations that indicate the zinc is in excess.

1

2

[ 2 ]

Question (ii)

(ii)

Name the filtrate.

[ 1 ]

Question (iii)

(iii)

Name two compounds which both react with dilute sulfuric acid to produce aqueous zinc sulfate.

1

2

[ 2 ]

Question (b)

(b)

Nickel(II) sulfate crystals contain water of crystallisation.

When nickel(II) sulfate crystals, NiSO4⋅xH2O\mathrm{NiSO}_{4} \cdot x \mathrm{H}_{2} \mathrm{O}, are heated, they give off water.

NiSO4⋅xH2O( s)→NiSO4( s)+xH2O( g)\mathrm{NiSO}_{4} \cdot \mathrm{xH}_{2} \mathrm{O}(\mathrm{~s}) \rightarrow \mathrm{NiSO}_{4}(\mathrm{~s})+\mathrm{xH}_{2} \mathrm{O}(\mathrm{~g})

A student carries out an experiment to determine the value of x in NiSO4⋅xH2O\mathrm{NiSO}_{4} \cdot \mathbf{x} \mathrm{H}_{2} \mathrm{O}.
step 1 Nickel(II) sulfate crystals are weighed.
step 2 Nickel(II) sulfate crystals are heated.
step 3 The remaining solid is allowed to cool and is then weighed.
step 4 The remaining solid is heated again, allowed to cool and is then weighed.
step 5 Step 4 is repeated until there is no change in mass.

[ 1 ]

Question (i)

(i)

State the term used to describe crystals that contain water of crystallisation.

[ 1 ]

Question 4

[Maximum number: 1]

This question is about sulfuric acid and salts that are made from sulfuric acid.

Nickel(II) sulfate crystals contain water of crystallisation.

When nickel(II) sulfate crystals, NiSO4⋅xH2O\mathrm{NiSO}_{4} \cdot x \mathrm{H}_{2} \mathrm{O}, are heated, they give off water.

NiSO4⋅xH2O( s)→NiSO4( s)+xH2O( g)\mathrm{NiSO}_{4} \cdot \mathrm{xH}_{2} \mathrm{O}(\mathrm{~s}) \rightarrow \mathrm{NiSO}_{4}(\mathrm{~s})+\mathrm{xH}_{2} \mathrm{O}(\mathrm{~g})

A student carries out an experiment to determine the value of x in NiSO4⋅xH2O\mathrm{NiSO}_{4} \cdot \mathbf{x} \mathrm{H}_{2} \mathrm{O}.
step 1 Nickel(II) sulfate crystals are weighed.
step 2 Nickel(II) sulfate crystals are heated.
step 3 The remaining solid is allowed to cool and is then weighed.
step 4 The remaining solid is heated again, allowed to cool and is then weighed.
step 5 Step 4 is repeated until there is no change in mass.

State the term used to describe crystals that contain water of crystallisation.

Question 5

[Maximum number: 4]

Question (a)

(a)

Lead(II) bromide, PbBr2\mathrm{PbBr}_{2}, is an insoluble salt and is made by precipitation.

[ 4 ]

Question (i)

(i)

Name two aqueous solutions that produce a precipitate of lead(II) bromide when they are mixed.

1

2

[ 2 ]

Question (ii)

(ii)

Describe how to produce a pure sample of lead(II) bromide from the mixture of aqueous solutions in (a)(i).

[ 2 ]

Question 6

[Maximum number: 1]

P is a hydrated metal salt with a blue colour. When P is heated, water is given off, leaving solid Q.
R is a hydrated metal salt with a pink colour. When R is heated, water is given off, leaving solid S.
Which row gives the name of P and the colour of S ?

name of P

colour of S

hydrated cobalt(II) chloride

blue

hydrated cobalt(II) chloride

white

hydrated copper(II) sulfate

blue

hydrated copper(II) sulfate

white

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