2025 ACTUAL AQA GCSE COMBINED SCIENCE: TRILOGY Higher Tier 8464/C/2H Chemistry Paper 2, Exams of Chemistry

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Please write clearly in block capitals. Centre number Candidate number Surname Forename(s) Candidate signature GCSE COMBINED SCIENCE: TRILOGY Higher Tier Chemistry Paper 2H | declare this is my own work. Friday 13 June 2025 Morning Time allowed: 1 hour 15 minutes Materials For Examiner’s Use For this paper you must have: ~ ° aruler Question Mark * ascientific calculator 1 « the periodic table (enclosed). Instructions e Use black ink or black ball-point pen. Pencil should only be used for drawing. Fill in the boxes at the top of this page. 6 Answer all questions in the spaces provided. If you need extra space for your answer(s), use the lined pages at the end of this book. Write the question number against your answer(s). ¢ Do all rough work in this book. Cross through any work you do not want to be marked. ¢ Inall calculations, show clearly how you work out your answer. 2 3 4 5 TOTAL Information e The maximum mark for this paper is 70. ¢ The marks for questions are shown in brackets. « You are expected to use a calculator where appropriate. « You are reminded of the need for good English and clear presentation in your answers. J 64C24H01 2584 8464/C/2H IB/M/Jun25/G4007/E7 Dodecane is an alkane. [o/1}.[4] The general formula for alkanes is CpHon+2 A molecule of dodecane has 12 carbon atoms. Complete the formula of dodecane. [1 mark] Cc H A student investigated the effect of changing the temperature on the viscosity of dodecane. Figure 1 shows the apparatus. Figure 1 Cup Dodecane i Dodecane flowing out through hole om? --100 E oO --80 E oO 60 Measuring cylinder Fo to collect dodecane -40 E o --20 Eo WN __ Do not write outside the box Do not write outside the Figure 2 shows the results. box Figure 2 T TTT T T Hot FEA { mm t t i 1 im 120 FEE | t rH T t Tt T t Cet tt Cet 100 ---—-\ ma | t | CH | im rt TT \ cH i | in ee i. HH mt 80 rH rH Time taken Het AG SO ee ee r to collect t | | t | t 40 cm? of | cH | t } rH t dodecane 69 t \ ct | tt i in seconds f Ht | | os oS oe a coo OS Se Oe Ne Oe ee ee tH cH f | a it i inn i it 40 im H COCA EE eee LH a CoCr et cH Too | | t | t tH t cH | eaene bene (a Gee ceed ceane tunes euebdin Cd eeee nee CEH TH { cH | | | PECEEEE rere reer PEPER EEE eer eee eee Tro i { { { 0 HH t t t t 20 30 40 50 60 70 80 Temperature of dodecane in °C. [o[1].[4] Predict the time taken to collect 40 cm? of dodecane at 75 °C. You should extend the line of best fit on Figure 2. [2 marks] Time taken = s INI IBIM/Jun25/8464/C/2H 4 [0[1].[5| The higher the viscosity, the slower dodecane flows. Explain how the trend in Figure 2 shows the effect of an increase in temperature on the viscosity of dodecane. [2 marks] Do not write outside the box Turn over for the next question 05 Turn over > IB/M/Jun25/8464/C/2H 5 Do not write outside the Explain how the percentages of gases have changed from Earth’s early atmosphere box to Earth’s atmosphere today. You should refer to all three gases in Table 1. [6 marks] Extra space [0] 2].[3| Methane is a greenhouse gas. Give two ways to reduce methane emissions into the atmosphere. [2 marks] Turn over > 07 IB/M/Jun25/8464/C/2H 7 Do not write itside the The percentage of sulfur dioxide in the Earth’s atmosphere increased between OK 1850 and 1980. [o]2].[4} Describe how sulfur dioxide emissions are produced. [2 marks] [o[2].[5| Give one harmful effect of sulfur dioxide emissions. [1 mark] [o[2].[6| Suggest one reason why the percentage of sulfur dioxide in the Earth's atmosphere has decreased since 1980. [1 mark] 14 08 IBIM/Jun25/8464/C/2H 8 10 Do not write outside the Crude oil is a finite resource found in rocks. bok [o[3].[14] What is meant by a ‘finite’ resource? [1 mark] [o[3].[2| Most of the compounds in crude oil are hydrocarbons. Define the term ‘hydrocarbon’. [1 mark] INI IBIM/Jun25/8464/C/2H 10 11 Do not write outside the [0] 3].[3] Crude oil found in different areas has different compositions. box Table 2 shows the percentage (%) composition of crude oil from one area. Table 2 9 Fraction Percentage ( %) Petrol 31.3 Kerosene 13.4 Diesel oil 14.4 Heavy fuel oil 40.9 The volume of crude oil is measured in a unit called ‘barrels’. 1 barrel = 159 dm? Calculate the volume of petrol in dm? in 90 barrels of crude oil. Give your answer to 3 significant figures. [4 marks] Volume of petrol (3 significant figures) = dm? Turn over > 11 IB/M/Jun25/8464/C/2H 11 13 Do not write outside the This question is about methanol. bok [0[4].[1] Methanol is used in screenwash. Screenwash is used to keep car windscreens clean. Screenwash is a formulation. Define the term ‘formulation’. [1 mark] Question 4 continues on the next page Turn over > IM IB/M/Jun25/8464/C/2H 13 (o[4][2] 14 Carbon monoxide and hydrogen are used to produce methanol. The conditions used in the production of methanol are: e high temperature e high pressure e acatalyst. The equation for the reaction is: CO(g) + 2H(g) = CHsOH(g) 91 kJ/mol of energy is transferred during the exothermic forward reaction. How much energy is transferred when methanol is decomposed into carbon monoxide and hydrogen? Tick (“) one box. < 91 kJ/mol 91 kJ/mol > 91 kJ/mol [1 mark] [0[4].[3| A scientist developed a principle to predict the effect of changing conditions on a system at equilibrium. What was the name of the scientist? [1 mark] 14 IBIM/Jun25/8464/C/2H Do not write outside the box 14 16 Do not write outside the Explain the effect of using a catalyst on the rate of production of methanol. box [3 marks] [0[4].[8| The catalyst allows the reaction to take place at a lower temperature. Explain one advantage of using a lower temperature in the production of methanol. Do not refer to the position of equilibrium in your answer. [2 marks] [0[4].[9]| Methanol (CH3OH) can also be produced by reacting carbon dioxide with hydrogen. Water is the other product of the reaction. Write a balanced equation for the reaction. [2 marks] + => + 15 16 IBIM/Jun25/8464/C/2H 16 17 Do not write outside the box Turn over for the next question DO NOT WRITE/ON THIS PAGE ANSWER IN THE/SPACES PROVIDED Turn over > IMI IB/M/Jun25/8464/C/2H 17 19 Do not write outside the [0[5].[1] What is the dependent variable in this investigation? box [1 mark] [o[5].[2| The equation for the reaction is: NazS203(aq) + 2HCl(aq) — 2NaCl(aq) + S(s) + SO2(g) + H20(I) The mixture becomes cloudy as the reaction takes place. Explain why the mixture becomes cloudy. [2 marks] [0[5].[3| Explain the effect of changing the concentration of the sodium thiosulfate solution on the rate of reaction. [3 marks] Turn over > 9 IB/M/Jun25/8464/C/2H 19 1 20 Do not write outside the A different student reacted magnesium with hydrochloric acid. box Figure 4 shows the apparatus. Figure 4 Gas syringe Hydrochloric acid Magnesium This is the method used. 1. Measure 50 cm of hydrochloric acid into a conical flask. 2. Add 0.1 g of magnesium ribbon to the conical flask. 3. Insert the stopper into the conical flask as quickly as possible. 4. Start a timer. 5. Record the volume of gas collected every 20 seconds for 5 minutes. 6. Repeat steps 1 to 5 using different concentrations of hydrochloric acid. [0[5].[4] Why is the stopper inserted into the conical flask as quickly as possible in step 3? [1 mark] 20 IBIM/Jun25/8464/C/2H 20