AQA GCSE Separate Science Chemistry – Paper 2 Higher Tier Predicted Paper 2023 WITH marking scheme

AQA GCSE Separate Science Chemistry – Paper 2 Higher Tier Predicted Paper 2023 WITH marking scheme Name …………………………………………………………………… Date ………………… 1 hour 45 minutes allowed. You may use a calculator and an AQA periodic table. Grade boundaries These are VERY rough guesses! Getting a 7 on this paper does not guarantee you the same mark in the exam. • 9 70% • 8 60% • 7 50% • 6 45% • 5 35% • 4 30% • 3 25% 01 a) Alkanes are hydrocarbons. Define the term hydrocarbon. [2 marks] b) The general formula for alkanes is CnH2n+2, i. Give the formula for an alkane that has 3 carbons. [1 mark] C H ii. Give the specific name for this alkane. [1 mark] iii. Draw this alkane. [3 marks] C C C c) Alkanes are often very long chains; these are found in the ground as crude oil. Crude oil is a mixture of different length hydrocarbon chains. Explain why crude oil needs to be refined before it can be used. [3 marks] d) A student said that “fractional distillation can be used to separate all types of mixtures”. Discuss if this student is correct or not. [3 marks] e) Crude oil also has alkenes mixed in. Describe the differences between alkanes and alkenes and how you can identify an alkene. [4 marks] 02 a) Water and carbon dioxide are products of combustion. Write a word equation for the complete combustion of a hydrocarbon. [1 mark] b) Describe how you could test a gas to identify carbon dioxide. [2 marks] c) Water and carbon dioxide are both greenhouse gases. Name another greenhouse gas. [1 mark] d) Describe one activity that increases the levels of carbon dioxide in the atmosphere. [2 marks] e) These gases contribute to the greenhouse effect. Describe how these gases can cause the atmosphere to act like a greenhouse. [6 marks] f) Describe five effects of climate change. [5 marks] 03 Sodium thiosulphate reacts with hydrochloric acid resulting in a change in the appearance of the solution. a) Balance the equation for this reaction: [2 marks] Na2S2O3(aq) + HCl(aq) → NaCl(aq) + H2O(l) + SO2(g) + S(s) b) The end point of the experiment is when a cross placed under the conical flask is no longer visible. Use the equation to identify and explain which product is responsible for the change in appearance. [2 marks] c) One product of this reaction is sulfur dioxide which is a polluting gas. Give a common source of sulfur dioxide. [1 mark] d) As the temperature of the reaction increases so does the rate of the reaction. It is a bad idea to do this reaction above 60C. Use the equation to suggest why. [2 marks] e) Explain why the rate of reaction increases as the temperature increases. [3 marks] f) A student wanted to determine if the rate of reaction was affected by the concentration of hydrochloric acid. Suggest a method that the student could use to investigate this. [5 marks] 04 a) Catalysts can influence the rate of a reaction. Explain how. [2 marks] b) Give the name of the catalyst commonly found in biological systems. [1 mark] c) Sketch a reaction profile for a reaction, with two lines on it. One line for an uncatalysed reaction and a second for a catalysed reaction. [5 marks] d) Internal combustion engines as used in cars do not have a ready supply of oxygen, so incomplete combustion takes place. This produces carbon monoxide instead of carbon dioxide as a waste gas. % volume of gas Gas Without catalytic convertor With catalytic convertor Carbon monoxide 6.5 2.3 Hydrocarbons 15.6 9.2 Platinum is used in catalytic convertors in cars. This converts carbon monoxide to carbon dioxide, and hydrocarbons into water and carbon dioxide before these gases is released into the air. Suggest the advantages and disadvantages of doing this. [4 marks] e) Catalysts are also used in industrial processes. State the metal catalyst that is used in the Haber Process. [1 mark] f) Explain the affect that the catalyst has on rate of production of ammonia and the equilibrium in the reaction. You should give the equation for the production of ammonia in your answer. [4 marks] 05 Humans rely on the resources that the Earth provides to survive. a) Some of these resources are finite. Define the term ‘finite’. [1 mark] b) List two reasons we use the Earth’s resources. [2 marks] c) Metal ores that are suitable to be mined out of the earth are becoming increasingly rare. This has led to older copper-based phone networks being turned off at the end of 2025 and people switching to fibre optics-based networks. Efforts are needed to find new ways to extract copper from low grade ores that cannot be mined. Two of these methods are phytomining and bioleaching. i. Describe the method of phytomining. [3 marks] ii. Describe the method of bioleaching. [3 marks] iii. Compare the advantages and disadvantages of bioleaching and phytomining. [4 marks] d) Copper is often used in alloys. Name an alloy that include copper. [1 mark] e) From 1971 to 1992 2 pence coins were made from a copper alloy. From 1992 to the present day, they have been made from copper plated steel. Suggest why the composition of the coins changed after 1992. [1 mark] f) Describe why alloys are used in most everyday metals. [2 marks] a) Name the structure of DNA. [1 mark] b) DNA hold the instructions to make amino acids, which in turn make proteins. Describe the link between DNA and proteins. [3 marks] c) Name the two different functional groups in an amino acid. [2 marks] d) Describe the reaction that joins two amino acids together. [2 marks]