11 mark
Higher Only
Lemon juice can be described as a weak acid.
What is the pH value for a weak acid?
pH 1
pH 4
pH 7
pH 14
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Types of Chemical Reactions (OCR Gateway GCSE Chemistry: Combined Science)
Exam Questions
2 hours35 questions21 mark
What is the name of the gas made when zinc carbonate reacts with hydrochloric acid?
Carbon dioxide
Chlorine
Hydrogen
Oxygen
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31 mark
Which of these pH values shows the pH of a strong acid?
1
5
7
10
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41 mark
What is the name of the gas made when magnesium reacts with sulfuric acid?
Carbon dioxide
Carbon monoxide
Hydrogen
Oxygen
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51 mark
Calcium reacts with hydrochloric acid to form the salt, calcium chloride and another product.
calcium + hydrochloric acid → calcium chloride + ___________
What is the unknown product?
Water
Oxygen
Hydrogen
Carbon dioxide
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61 mark
A solution of hydrochloric acid is pH 2. The acid solution is diluted, and the pH is now 3.
By what factor is the acid solution diluted?
5
10
100
1000
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71 mark
Which diagram represents a strong, dilute acid?
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11 mark
A student added some sulfuric acid gradually to a solution of ammonia until it was in excess.
What happens to the pH during this reaction?
| pH of ammonia at start | pH after addition of excess sulfuric acid | |
| A | 11 | 7 |
| B | 7 | 13 |
| C | 11 | 2 |
| D | 3 | 8 |
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2
1 mark
1 markWhat is the ionic equation for neutralisation?
2H+ (aq) + OH- (aq) → H2O (l)
H+ (aq) + OH- (aq) → H2O (aq)
H+ (aq) + OH- (aq) → H2O (l)
2H2 + O2 → 2H2O
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31 mark
Zinc is extracted from zinc oxide by reduction.
zinc oxide + carbon → zinc + carbon dioxide
Which element acts a reducing agent during this process?
Hydrogen
Oxygen
Carbon
Zinc
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41 mark
Sodium hydroxide reacts with sulfuric acid.
__NaOH + __H2SO4 → __Na2SO4 + __H2O
Which numbers correctly balance the equation?
1, 2, 2, 1
2, 2, 1, 2
2, 1, 1, 2
1, 1, 2, 2
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51 mark
Sodium hydroxide reacts with hydrochloric acid. Sodium chloride and water are made.
What is the name of this type of reaction?
Neutralisation
Oxidation
Reduction
Thermal decomposition
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61 mark
Neutralisation occurs when acids react with alkalis.
What is the ionic equation for neutralisation?
H+ + OH− → H2O
H- + OH+ → H2O
H+ + OH+ → H2O
H- + OH− → H2O
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71 mark
Look at the equation.
CH4 + 2O2 → CO2 + 2H2O
Which substance is oxidised in this reaction?
CH4
CO2
H2O
O2
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81 mark
Look at the equation.
CH4 + 2O2 → CO2 + 2H2O
Which substance is the oxidising agent in this reaction?
CH4
CO2
H2O
O2
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91 mark
A student measures the pH of an acid and an alkali.
He adds magnesium metal to the acid and to the alkali.
What results should he expect?
| Acid | Alkali | |||
| pH | Reaction with magnesium | pH | Reaction with magnesium | |
| A | Below 7 | No reaction | Above 7 | Magnesium fizzes |
| B | Below 7 | Magnesium fizzes | Above 7 | No reaction |
| C | Above 7 | Magnesium fizzes | Above 7 | No reaction |
| D | Above 7 | No reaction | Above 7 | Magnesium fizzes |
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101 mark
Which equation represents neutralisation?
2H+ → H2
H2O → H+ + OH-
H+ + OH- → H2O
2OH- → O2 + H2
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111 mark
Magnesium reacts with copper oxide.
Magnesium oxide and copper are made.
magnesium + copper oxide → magnesium oxide + copper
Which substance is the reducing agent?
Copper
Copper oxide
Magnesium
Magnesium oxide
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121 mark
Magnesium powder reacts with copper(II) oxide. Magnesium oxide and copper are made.
Mg + CuO → MgO + Cu
Which substance is the reducing agent?
Magnesium
Copper oxide
Magnesium oxide
Copper
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131 mark
Higher Only
The equation shows a reaction that involves both oxidation and reduction.
Fe2O3 + 2Al → Al2O3 + 2Fe
Which statement about reduction is correct?
The gain of oxygen and the gain of electrons by a substance
The gain of oxygen and the loss of electrons by a substance
The loss of oxygen and the gain of electrons by a substance
The loss of oxygen and the loss of electrons by a substance
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141 mark
Which equation represents neutralisation?
4H+ → 2H2
H2O → 2H+ + O2–
H+ + OH– → H2O
O2 + H2 → H2O + O2–
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11 mark
1 markA solution of sulfuric acid with a pH of 4 has a hydrogen ion concentration of 1 x 10-4 mol/dm3.
Another acid has a hydrogen ion concentration of 1 x 10-6 mol/dm3.
What is the pH of this acid?
2
3
5
6
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21 mark
A reaction took place between iron sulfate and magnesium.
iron(II) sulfate + magnesium → magnesium sulfate + iron
Which species has been oxidised?
Iron
Magnesium
Sulfur
None of the above
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31 mark
A displacement reaction occurs between zinc and copper chloride.
Which half equation correctly shows the change that zinc undergoes?
Zn2+(aq) + 2e- → Zn (s)
Zn (s) + 2e- → Zn2+ (aq)
Zn2+ (aq) → Zn (s) + 2e-
Zn (s) → Zn2+ (aq) + 2e-
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41 mark
1 markHigher Only
A student investigates some acids.
She has a solution of hydrochloric acid of concentration 0.01 mol / dm3.
This solution has a pH of 2.
She increases the concentration of hydrochloric acid from 0.01 mol / dm3 to 0.1 mol / dm3.
What is the pH of this new solution?
0
1
3
12
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51 mark
Which statement about an oxidising agent is correct?
It gains oxygen in a reaction.
It is oxidised in a reaction.
It is reduced in a reaction.
It loses electrons in a reaction.
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61 mark
This is the balanced symbol equation for the reaction of copper oxide with carbon.
2CuO + C → 2Cu + CO2
What happens to the copper oxide in this reaction?
It is neutralised.
It is oxidised.
It is reduced.
It is thermally decomposed.
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