11 mark
When solid sodium chloride is mixed with water, sodium chloride solution forms.
What name is given to the process of mixing a solid with water to form a solution?
| A | Crystallising |
| B | Diluting |
| C | Dissolving |
| D | Melting |
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Preparation of Salts (Cambridge O Level Chemistry)
Exam Questions
4 hours43 questions21 mark
Different salts can be prepared by titrating an alkali with an aqueous acid.
Three pieces of apparatus, P, Q and R, used to measure volumes of liquid are shown below.
What are the names of the three pieces of apparatus, P, Q and R?
| P | Q | R | |
| A | pipette | burette | measuring cylinder |
| B | burette | pipette | conical flask |
| C | pipette | volumetric flask | burette |
| D | burette | pipette | measuring cylinder |
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31 mark
The chemical equation for the preparation of lead(II) sulfate is written below.
Pb(NO3)2 (___) + Na2SO4 (___) → PbSO4 (___) + 2NaNO3 (___)
What are the state symbols for each substance in this reaction?
| A | aq, aq, s, aq |
| B | aq, aq, s, s |
| C | s, aq, aq, s |
| D | s, aq, s, aq |
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41 mark
A student making copper sulfate crystals used the method shown.
Unreacted copper carbonate was left over as it had been added in excess.
What is the reason for adding it in excess and what would step 3 be of this method?
| reason for adding in excess | step 3 | |
| A | to produce a greater amount of salt crystals | filtration |
| B | to improve the colour intensity of the crystals | crystallisation |
| C | to ensure all the acid reacts | filtration |
| D | to increase the rate of reaction | evaporation |
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51 mark
When an aqueous salt is crystallised, some water can be retained within the structure of the salt.
What is the name given to the type of salt that forms?
| A | anhydrous salt |
| B | dehydrated salt |
| C | hydrated salt |
| D | soluble salt |
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11 mark
A student wanted to prepare copper(II) sulfate crystals by reacting solid copper(II) oxide to a solution of hot sulfuric acid.
An extract from the method section of the experimental handout is shown below:
Add the copper(II) oxide in small amounts to the hot acid in the reaction flask and stir until it is …..1…... When the reaction has gone to completion the copper(II) oxide will no longer …..2……, …..3….. and …..4….. the solution to obtain the copper(II) sulfate crystals.
| 1 | 2 | 3 | 4 | |
| A | in excess | precipitate | cool | dissolve |
| B | in excess | dissolve | filter | cool |
| C | reacting | dissolve | cool | filter |
| D | reacting | precipitate | filter | cool |
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21 mark
Which of the following methods to prepare a salt can be achieved using a burette and a pipette?
Nitric acid and calcium carbonate to prepare calcium nitrate.
Sulfuric acid and copper(II) oxide to prepare copper(II) sulfate.
Hydrochloric acid and zinc to prepare zinc chloride.
Hydrochloric acid and potassium hydroxide to prepare potassium chloride.
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31 mark
Copper(II) sulfate can be prepared by reacting solid copper(II) carbonate with hot sulfuric acid. The alkali solid is always added in excess.
Why is the solid reactant added in excess?
To ensure all of the acid reacts.
To make the reaction go faster.
To ensure all of the solid reactant has reacted.
To increase the product yield.
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41 mark
What is the correct sequence of steps for the preparation of a pure sample of lead(II) iodide from solid potassium iodide and lead(II) nitrate ?
Mixing → Dissolving → Filtration → Rinsing with distilled water → Drying
Rinsing with distilled water → Dissolving → Mixing → Filtration → Drying
Dissolving → Mixing → Filtration → Rinsing with distilled water → Drying
Dissolving → Filtration → Mixing → Rinsing with distilled water → Drying
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51 mark
Samples of two solids, P & Q, are separately dissolved in water and made into solutions.
Which combination of P & Q solutions, would give an insoluble product on mixing?
| P | Q | |
| A | potassium chloride | sodium hydroxide |
| B | ammonium chloride | potassium sulfate |
| C | sodium nitrate | magnesium sulfate |
| D | barium chloride | sodium sulfate |
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61 mark
Two incomplete statements about the preparation of an insoluble salt are given.
......1...... can be used to prepare insoluble salts, such as ......2...... .
The salt is collected by ...... 3...... and it is then ......4...... .
Which words correctly complete gaps 1–4?
|
|
1 |
2 |
3 |
4 |
|
A |
precipitation |
barium nitrate |
filtration |
evaporated |
|
B |
precipitation |
lead sulfate |
evaporation |
washed and dried |
|
C |
precipitation |
lead sulfate |
filtration |
washed and dried |
|
D |
titration |
barium nitrate |
evaporation |
washed and dried |
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71 mark
Which pair of reagents is suitable for preparing a pure sample of copper(II) chloride crystals?
aqueous copper(II) nitrate and aqueous sodium chloride
copper and aqueous sodium chloride
copper and dilute hydrochloric acid
copper(II) oxide and dilute hydrochloric acid
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11 mark
A student is provided with solutions of dilute hydrochloric acid, dilute sulfuric acid, solid magnesium oxide, zinc carbonate and copper.
How many different salts could the student make?
2
3
4
6
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21 mark
A substance reacts with dilute H2SO4 to form a salt which is separated by filtration.
What is the substance?
Aqueous sodium hydroxide
Aqueous barium chloride
Copper
Copper(II) carbonate
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31 mark
Which statement is correct?
Anhydrous copper sulfate will decrease in mass on gentle warming
Water of crystallisation is the number of water molecules present in hydrated crystals
All soluble salts contain water of crystallisation
Hydrated copper(II) sulfate has the formula CuSO4.2H2O
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41 mark
Which method(s) of salt preparation could be used to prepare a sample of magnesium chloride?
1 Titration
2 Reaction of an acid with excess metal
3 Reaction of an acid with excess insoluble base
1 and 2 only
1 and 3 only
2 and 3 only
1 only
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51 mark
Silver chloride can be prepared by the reaction of silver nitrate solution with potassium chloride solution.
Which statement about the preparation is correct?
To get the maximum yield of product you need to have excess silver nitrate
To get the maximum yield of product you need to have excess potassium chloride
Equal volumes of the two solutions should be used
Equal concentrations of the two solutions should be used
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