AQA GCSE Chemistry Paper 1

Question 1

This question is about salts.
Green copper carbonate and sulfuric acid can be used to produce blue copper sulfate crystals.
Excess copper carbonate is added to sulfuric acid. Give three observations you would make. (3 marks)

Answer 1

any three from:
* green solid / powder * colourless solution
* blue solution formed
* copper carbonate disappears
* fizzing / effervescence or
bubbles (of gas)
* stops fizzing
* solid / powder left at the end or
copper carbonate left at the end

Question 2

How can the excess copper carbonate be removed? (1 mark)

Answer 2

filtration
or
filter

Question 3

The pH of the solution changes during the reaction. What is the pH of the solution at the end of the reaction? (1 mark)

Answer 3

7

Question 4

Copper carbonate and sulfuric acid react to produce copper sulfate. What type of reaction is this? (1 mark)

Answer 4

Neutralisation

Question 5

Potassium sulfate contains K+ and SO42– ions. What is the formula of potassium sulfate? (1 mark)

Answer 5

K2SO4

Question 6

The experiment is repeated 4 times.
The volumes of oxygen collected in the 4 experiments are:
6 cm3 9 cm3 10 cm3 11 cm3

The mean volume of oxygen collected in the 4 experiments is 9 cm3

The measure of uncertainty is the range of a set of measurements about the mean.

What is the measure of uncertainty in the 4 experiments? (4 marks)

Answer 6

9 ±3 cm3

Question 7

The potassium sulfate solution has 0.86 g of potassium sulfate dissolved in 25 cm3 of water.

Calculate the mass of potassium sulfate needed to make 1.0 dm3 of solution. (3 marks)

Answer 7

(conversion)
( 25 = ) 0.025 (dm3) 1000
(concentration =) 0.86
0.025
= 34.4 (g per dm3)

OR
(conversion) 1000 (1)
25
= 40 (1)
(40 × 0.86)
= 34.4 (g per dm3) (1)

OR
(concentration =) 0.86 (1)
25
= 0.0344 (1)
(conversion)
(0.0344 × 1000)
= 34.4 (g per dm3) (1)

Question 8

Plan an investigation to find the order of reactivity of three metals.

You should use the temperature change when each metal reacts with hydrochloric acid. (6 marks)

• Learn one answer

Answer 8

5-6 Marks
Level 3: The method would lead to the production of a valid outcome. All key steps are identified and logically sequenced.

• measure volume of (hydrochloric) acid
• into a suitable container eg polystyrene cup
• measure the initial temperature (of hydrochloric acid)
• with a thermometer
• add stated mass of one metal
• stir
• measure the highest temperature reached of the solution or
  measure temperature reached after a set time period
• determine the temperature difference
• repeat
• repeat for each metal
• with same mass
• in same physical state (powder, lump, etc)
• with the same volume and / or concentration of (hydrochloric)
  acid
• use results to arrange metals in order of reactivity
• most reactive metal has the largest temperature change

to access level 3 there must be an indication of how the temperature change is determined with the same mass of the 3 different metals reacted with the same volume of (hydrochloric) acid

Question 9

This question is about Group 7 elements. What are the Group 7 elements known as? (1 mark)

Answer 9

halogens

Question 10

Why do Group 7 elements react in similar ways? (1 mark)

Answer 10

all have 7 electrons in outer shell
or
all have 7 outer electrons

Question 11

What is the molecular formula of a chlorine oxide molecule? (1 mark)

Answer 11

Cl2O7

Question 12

Explain the trend in the melting points of the Group 7 elements. (3 marks)

Answer 12

(the) molecules increase in size going down the group

(so the) forces between the molecules increase

Question 13

What is the state symbol for bromine at –50 °C? (1 mark)

• Include brackets to be safe

Answer 13

(s)

Question 14

Evaporation and boiling occur at the surface of bromine at its boiling point.

Name one more process that happens at the surface of bromine at its boiling point. (1 mark)

Answer 14

condensation

Question 15

An alloy of aluminium contains small amounts of other metals. Explain why other metals are added to aluminium. (4 marks)

Answer 15

other metal atoms have different
sizes to aluminium atoms

(so) the layers of aluminium
atoms are distorted

(so) the layers cannot slide
(which) makes the alloy harder

Question 16

Hydrogen chloride dissolves in water to produce hydrochloric acid. Hydrochloric acid is a strong acid.
What is meant by the term strong acid? (1 mark)

Answer 16

completely ionises in aqueous solution

Question 17

Describe how magnesium can be used to distinguish between a strong acid and a weak acid of the same concentration. (2 marks)

Answer 17

fizzing / effervescence
or
magnesium disappears

at a greater rate with a strong acid

Question 18

The concentration of hydrochloric acid is increased by a factor of 100 What is the change in pH? (2 marks)

Answer 18

(pH) decreases by (a unit of) 2

Question 19

The reaction between sodium and titanium chloride is a redox reaction. Write a half-equation to show that sodium is oxidised in this reaction. (2 marks)

Answer 19

Na → Na+ + e–

Question 20

108 g of aluminum reacts with 1.21 kg of copper chloride to produce copper.

The equation for the reaction is:
2Al + 3CuCl2 → 3Cu + 2AlCl3

Calculate the maximum mass of copper produced in grams (g). You should determine the limiting reactant.

Relative atomic masses (Ar): Al = 27 Cu = 63.5
Relative formula masses (Mr): CuCl2 = 134.5 AlCl3 = 133.5 (6 marks)

• Include all workings in your answer no matter how small! (even 1+1 = 2 for example)

Answer 20

method 1:
(moles of Al = 108 =) 4 27
(moles CuCl2 = 1210 = ) 8.996 134.5
(identifying limiting reactant) 4 moles Al gives 6 moles Cu
8.996 moles CuCl2 gives 8.996 moles Cu
therefore aluminium is the limiting reactant
(mass of Cu = 2 × 3 × 63.5) = 6 × 63.5
= 381 (g)

Question 21

Sodium metal and sodium chloride are both able to conduct electricity. Describe how sodium metal conducts electricity. (2 marks)

Answer 21

delocalised electrons

carry (electrical) charge through the metal / sodium

Question 22

Explain how sodium chloride can conduct electricity. (2 marks)

Answer 22

(conducts electricity) when liquid / molten or
(conducts electricity) in (aqueous) solution

(because) ions
(ions) are free to move
or
(ions) allow charge to flow

Question 23

What is meant by ‘isotopes’?
You should refer to subatomic particles. (2 marks)

Answer 23

(atoms with the) same number of protons

BUT

(with) different numbers of neutrons

Question 24

Acids react to produce salts.
Universal indicator is added to water and then nitric acid is added to the mixture.

Give the colour change when nitric acid is added to the mixture of universal indicator and water. (1 mark)

A - Blue to red
B - Green to purple
C - Green to red
D - Red to purple

Answer 24

C - Green to red

Question 25

What happens to the pH of water when nitric acid is added? (1 mark)

Answer 25

Decreases

Question 26

What is the state symbol for nitric acid? (1 mark)

Answer 26

(aq)

Question 27

Give two observations that would be made when zinc carbonate is added to nitric acid until the zinc carbonate is in excess. (2 marks)

Answer 27

Any two from:
* (white) solid disappears
* fizzing / bubbles / effervescence
* (then) stops fizzing
* (white) solid left at the end / bottom

Question 28

The formula of the zinc ion is Zn2+ The formula of the nitrate ion is NO3–

What is the formula for zinc nitrate? (1 mark)

Answer 28

Zn(NO3)2

Question 29

Acids react with insoluble metal oxides to produce salts.
Plan a method to produce a pure, dry sample of the soluble salt copper chloride from
an acid and a metal oxide. (6 marks)

• Commonly asked, learn as a standard answer.

Answer 29

5-6 Marks
Level 3: The method would lead to the production of a valid outcome. The key steps are identified and logically sequenced.

Indicative Content:
* react hydrochloric acid
* (with) copper oxide
* in a suitable container
* warm (hydrochloric) acid
*
add copper oxide
* until is in excess or
until solid remains
* stir
* filter excess copper oxide
* pour solution / filtrate into evaporating basin
* use of water bath
* to heat gently
* leave to cool / crystallise

For level 3 the correct chemicals must have been selected.

Question 30

Carbon can exist in a number of different structures. The first fullerene to be discovered was Buckminsterfullerene. What is the formula of Buckminsterfullerene? (1 mark)

Answer 30

C60

Question 31

Graphite is a form of carbon.
Explain why graphite conducts electricity. (2 marks)

Answer 31

(graphite has) delocalised electrons

(so the delocalised electrons) carry electrical charge through the structure

Question 32

Steel is an alloy of iron and carbon. Explain why steel is harder than iron. (3 marks)

Answer 32

Carbon atoms have different sizes to iron atoms / ions

(so carbon atoms) distort the layers of iron atoms / ions

(therefore) the layers cannot slide

Question 33

Hydrogen gas and oxygen gas are produced when sodium sulfate solution is electrolysed.
Explain how oxygen gas is produced in the electrolysis of sodium sulfate solution. (4 marks)

Answer 33

water molecules
break down to produce OH– ions
(which are) attracted to the positive electrode

(where OH– ions are) oxidised
or
(where OH– ions) lose electrons

Question 34

Copper reacts with oxygen to produce copper oxide. 63.5 g of copper produces 79.5 g of copper oxide.
Calculate the mass of copper oxide produced when 0.50 g of copper reacts with oxygen.
Give your answer to 3 significant figures. (3 marks)

• Make sure it is 3 significant figures else you will lose a mark!
• Write down all markings

Answer 34

(mass of copper oxide =)
79.5 ×0.5 63.5
= 0.62598 (g) = 0.626 (g)

Question 35

Iron reacts with oxygen to produce an oxide of iron.
0.015 moles of iron reacts with 0.010 moles of oxygen gas (O2).

Determine:
* the formula of the iron oxide produced
* the balanced symbol equation for the reaction. (4 marks)

• Take each step (part of question) at a time
• Don’t get overwhelmed

Answer 35

3:2 ratio Fe : O2 (molecules)
or
3:4 ratio Fe : O (atoms) (formula)

Fe3O4

3Fe + 2O2 Fe3O4

Question 36

Methane, ethane, propane and butane all react with oxygen to produce carbon dioxide and water.
Suggest why a mixture of methane and oxygen does not react at room temperature.

Answer in terms of particles. (2 marks)

Answer 36

particles collide

(but at room temperature) particles have insufficient energy
or
(but) have energy less than the activation energy (so collisions are not successful)