Chemistry
GCSE Chemistry Daily Practice (Higher)
Instructions
- • Use black ink or black ball-point pen. Draw diagrams in pencil.
- • Answer all questions in the spaces provided.
- • Do all rough work in this question paper. Cross through any work you do not want to be marked.
- • Show all your working out — marks may be awarded for correct working even if the answer is wrong.
Information
- • The total mark for this paper is 33.
- • The marks for each question are shown in brackets — use this as a guide as to how much time to spend on each question.
- • Questions labelled with an asterisk (*) are where the quality of your written communication will be assessed.
Answer all questions in the spaces provided.
Copper can be extracted from copper sulfate solution by electrolysis. (a) Write the half equation for the reaction at the cathode. [2 marks] (b) Write the half equation for the reaction at the anode. [2 marks] (c) Explain, in terms of electron transfer, why the reaction at the cathode is reduction. [1 mark] (d) A student passes a current of 0.5 A for 30 minutes. Calculate the mass of copper deposited. (Ar of Cu = 63.5, Faraday constant = 96,500 C/mol) [3 marks]
A student investigates the rate of reaction between marble chips (CaCO₃) and hydrochloric acid at two different temperatures. CaCO₃ + 2HCl → CaCl₂ + H₂O + CO₂ (a) The student measures gas volume every 30 seconds. At 20°C the reaction produces 48 cm³ of gas in 3 minutes. At 40°C it produces 48 cm³ in 80 seconds. Calculate the mean rate of reaction at each temperature. [2 marks] (b) Explain, using collision theory, why the rate is higher at 40°C. [3 marks] (c) Explain why the total volume of gas is the same at both temperatures. [1 mark] (d) Suggest how the student could increase the total volume of gas produced. [1 mark]
Butane (C₄H₁₀) undergoes complete combustion. (a) Write a balanced symbol equation for this reaction. [2 marks] (b) Use the bond energies below to calculate the overall energy change for this reaction. Bond | Energy (kJ/mol) C−H | 413 C−C | 347 O=O | 498 C=O | 805 O−H | 464 (c) Is this reaction exothermic or endothermic? Explain using your answer to (b). [2 marks]
Iron(III) oxide is reduced by carbon in a blast furnace. Fe₂O₃ + 3CO → 2Fe + 3CO₂ A sample of iron ore contains 75% Fe₂O₃ by mass. The ore sample weighs 500 kg. (a) Calculate the mass of Fe₂O₃ in the sample. [1 mark] (b) Calculate the maximum mass of iron that could be produced. [3 marks] (c) In practice, only 280 kg of iron is obtained. Calculate the percentage yield. [2 marks]
*Compare the structure, bonding and properties of diamond, graphite and fullerenes (C₆₀). Explain how the structure of each relates to its properties. [6 marks]
End of Questions
Total marks: 33