CIE iGCSE Co-Ordinated Science C9.4 Reactivity series Exam Style Questions Paper 3
Question
(a) A student adds calcium and copper to separate test-tubes of cold water. Describe the reaction, if any, for each metal.
▶️Answer/Explanation
Calcium: Gas evolved / metal dissolves / white insoluble solid forms.
Copper: No change.
(b) The student reacts copper carbonate with dilute sulfuric acid. Copper(II) sulfate, carbon dioxide and water are made.
(i) Complete the word equation for this reaction.
▶️Answer/Explanation
Copper carbonate + sulfuric acid → copper sulfate + carbon dioxide + water.
(ii) Carbon dioxide gas is a greenhouse gas. State the name of one other greenhouse gas.
▶️Answer/Explanation
Methane.
(iii) The formula of copper(II) sulfate is CuSO4. State the number of different elements and the total number of atoms shown in this formula.
▶️Answer/Explanation
Number of elements: 3 (Copper, Sulfur, Oxygen).
Number of atoms: 6 (1 Cu, 1 S, 4 O).
(c) Copper oxide, CuO, is reduced to copper, Cu, by heating with carbon. The equation for the reaction is shown.
2CuO + C → 2Cu + CO2
(i) Explain how the equation shows that copper oxide, CuO, is reduced.
▶️Answer/Explanation
Copper oxide loses oxygen, which is the definition of reduction.
(ii) The reaction between copper oxide and carbon is exothermic. State what is meant by exothermic.
▶️Answer/Explanation
Exothermic reactions release energy to the surroundings, usually in the form of heat.
(iii) Name a metal, other than copper, that can be extracted from its ore by heating with carbon.
▶️Answer/Explanation
Iron.
Question
(a) Copper and sodium are metals. Copper is a transition element. Sodium is not a transition element. It is found in Group I of the Periodic Table. Some properties of metallic elements are listed.
Properties:
A: act as a catalyst
B: form coloured compounds
C: good conductor of electricity
D: good conductor of thermal energy
E: malleable
F: non-magnetic
State the letters (A to F) of the two properties that describe copper but do not describe sodium.
▶️Answer/Explanation
Answer: A and B
Copper is a transition metal and can act as a catalyst (A) and form coloured compounds (B). Sodium, being an alkali metal, does not exhibit these properties.
(b) Copper(II) oxide is heated with carbon. Copper and carbon dioxide are made.
(i) Construct the word equation for the reaction between copper(II) oxide and carbon.
▶️Answer/Explanation
Copper(II) oxide + carbon → copper + carbon dioxide
(ii) State the chemical test for carbon dioxide gas and the observation for a positive result.
▶️Answer/Explanation
Test: Bubble the gas through limewater.
Observation: The limewater turns cloudy/milky.
(iii) Explain why copper(II) oxide is described as a basic oxide.
▶️Answer/Explanation
Copper(II) oxide is a metal oxide, and metal oxides are generally basic. They react with acids to form salts and water, which is a characteristic of basic oxides.
(c) Metals can be coated with a layer of copper using electroplating. Electroplating uses the process of electrolysis. Use words from the list to complete the sentence to define the term electrolysis.
Each word may be used once or not at all.
covalent electricity gas ionic molten
solid solution time water
Electrolysis always involves the breakdown of …… compounds when …… or in aqueous …… by the passage of …… .
▶️Answer/Explanation
Electrolysis always involves the breakdown of ionic compounds when molten or in aqueous solution by the passage of electricity.
(d) Bronze is a mixture of copper and tin.
(i) State the term used to describe a mixture of metals.
▶️Answer/Explanation
Alloy
(ii) Apart from cost, suggest why bronze is used to make coins but pure copper is not used to make coins.
▶️Answer/Explanation
Bronze is tougher and stronger than pure copper, making it more durable for use in coins.