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Pearson Edexcel International GCSE (9–1)
Friday 13 June 2025
Morning (Time: 1 hour 15 minutes)
Chemistry
Paper
reference 4CH1/2CR
Total Marks
Instructions
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UNIT: 4CH
PAPER: 2CR
Pearson Edexcel International GCSE Chemistry (4CH1/2CR) Question
Paper 2 CR and Mark Scheme Summer 2025
The Periodic Table of the Elements 1 2 3 4 5 6 7 0 1 H hydrogen Key^1 _ The lanthanoids (atomic numbers 58 – 71) and the actinoids (atomic numbers 90 – 103) have been omitted. The relative atomic masses of copper and chlorine have not been rounded to the nearest whole number._* 2 ■ ■ ■ ■ 4 He helium 2 7 Li lithium 3 9 Be beryllium 4 relative atomic mass atomic symbol name atomic (proton) number 11 B boron 5 12 C carbon 6 14 N nitrogen 7 16 O oxygen 8 19 F fluorine 9 20 Ne neon 10 23 Na sodium 11 24 Mg magnesium 12 27 Al aluminium 13 28 Si silicon 14 31 P phosphorus 15 32 S sulfur 16
Cl chlorine 17 40 Ar argon 18 39 K potassium 19 40 Ca calcium 20 45 Sc scandium 21 48 Ti titanium 22 51 V vanadium 23 52 Cr chromium 24 55 Mn manganese 25 56 Fe iron 26 59 Co cobalt 27 59 Ni nickel 28
Cu copper 29 65 Zn zinc 30 70 Ga gallium 31 73 Ge germanium 32 75 As arsenic 33 79 Se selenium 34 80 Br bromine 35 84 Kr krypton 36 85 Rb rubidium 37 88 Sr strontium 38 89 Y yttrium 39 91 Zr zirconium 40 93 Nb niobium 41 96 Mo molybdenum 42 [98] Tc technetium 43 101 Ru ruthenium 44 103 Rh rhodium 45 106 Pd palladium 46 108 Ag silver 47 112 Cd cadmium 48 115 In indium 49 119 Sn tin 50 122 Sb antimony 51 128 Te tellurium 52 127 I iodine 53 131 Xe xenon 54 133 Cs caesium 55 137 Ba barium 56 139 La* lanthanum 57 178 Hf hafnium 72 181 Ta tantalum 73 184 W tungsten 74 186 Re rhenium 75 190 Os osmium 76 192 Ir iridium 77 195 Pt platinum 78 197 Au gold 79 201 Hg mercury 80 204 Tl thallium 81 207 Pb lead 82 209 Bi bismuth 83 [209] Po polonium 84 [210] At astatine 85 [222] Rn radon 86 [223] Fr francium 87 [226] Ra radium 88 [227] Ac* actinium 89 [261] Rf rutherfordium 104 [262] Db dubnium 105 [266] Sg seaborgium 106 [264] Bh bohrium 107 [277] Hs hassium 108 [268] Mt meitnerium 109 [271] Ds darmstadtium 110 [272] Rg roentgenium 111 Elements with atomic numbers 112 – 116 have been reported but not fully authenticated
2 Crude oil is a mixture of hydrocarbons. (a) Name the process used to separate crude oil into fractions. (1)
.................................................................................................................................................................................................................................................................................... (b) Give one use for the bitumen fraction. (1) .................................................................................................................................................................................................................................................................................... (c) The diagram shows the displayed formula of one of the alkanes in the refinery gases fraction. H H H H H C C C C H H H H H (i) Determine the molecular formula of this alkane. (1) .................................................................................................................................................................................................................................................................................... (ii) Name this alkane. (1) .................................................................................................................................................................................................................................................................................... (iii) Give the general formula of the homologous series of alkanes. (1) .................................................................................................................................................................................................................................................................................... (Total for Question 2 = 5 marks) 4 ■■■■
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(c) The equation shows the thermal decomposition of potassium permanganate. 2KMnO 4 → K 2 MnO 4 + MnO 2 + O 2 (i) Describe a test to show that oxygen gas is produced. (1)
.................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... (ii) Calculate the M r of K 2 MnO 4 (1) M r =.............................................................. (d) Potassium permanganate is an oxidising agent. Give a reason why potassium permanganate is an oxidising agent. (1) .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... (Total for Question 3 = 7 marks) ■■■■ 7 Turn over
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4 This question is about Group 1 metals. (a) A teacher adds a small piece of lithium metal to a trough containing water. (i) Complete the equation for the reaction between lithium and water by adding the state symbols. 2Li(................ ) + 2H 2 O(................ ) → 2LiOH(................ ) + H 2 ( ....... ) (ii) Give two observations made when the lithium is added to the water.
.................................................................................................................................................................................................................................................................................... 2............................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... (iii) The reaction produces 375 cm^3 of hydrogen gas at room temperature and pressure (rtp). Show, by calculation, that the mass of lithium added is between 0.20 g and 0.30 g. [1 mol of gas has a volume of 24 000 cm^3 at rtp] [for lithium, A r = 7] (3) 8 ■■■■
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5 This question is about metals and metal compounds. (a) The method used to extract a metal depends on the reactivity of the metal. Explain which method is used to extract sodium metal from sodium chloride. (2)
.................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... (b) The diagram shows the arrangement of particles in a pure metal. Explain why pure metals are soft. (2) .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... 10 ■■■■
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(c) The diagram shows the electronic structure of an atom of sodium and an atom of oxygen. Sodium Oxygen Describe, in terms of electrons, what happens when sodium reacts with oxygen. (2)
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6 A student does a titration to find the volume of phosphoric acid solution (H 3 PO 4 ) needed to neutralise a sample of potassium hydroxide solution (KOH). One of the products of the reaction is potassium phosphate. This is the student’s method.
- use a measuring cylinder to transfer 25 cm^3 of potassium hydroxide solution to a conical flask
- add two drops of an indicator
- fill a burette with phosphoric acid solution and record the initial reading on the burette
- add the acid to the conical flask
- record the final burette reading when the indicator changes colour This is the equation for the reaction. H 3 PO 4 (aq) + 3KOH(aq) → K 3 PO 4 (aq) + 3H 2 O(l) (a) Explain two improvements to the student’s method that would give more accurate results. (4) 1............................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... 2............................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... 14 ■■■■
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(c) Potassium phosphate solution reacts with calcium chloride solution. One of the products is the insoluble solid, calcium phosphate. (i) Complete the equation for the reaction. 2K 3 PO 4 (aq) +................ CaCl 2 (aq) → Ca 3 (PO 4 ) 2 (s) + ........ KCl(aq) (ii) The student reacts a solution containing 0.0400 mol of potassium phosphate with an excess of calcium chloride solution. The student obtains 5.70 g of calcium phosphate. Show that the percentage yield for the reaction is about 90% [for Ca 3 (PO 4 ) 2 M r = 310] 16
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(iii) Describe how the student can obtain a pure, dry sample of calcium phosphate from the mixture at the end of the reaction. (3)
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■■■■ The table shows some bond energies. Bond Bond energy in kJ / mol C H 414 C C 346 C O 358 O H 463 O O 498 C O 804 (i) Use the bond energies to show that the molar enthalpy change, Δ H , is about − 1300 kJ / mol. (3) 19 Turn over
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(ii) Complete the energy level diagram for the reaction between C 2 H 5 OH and O 2 energy (iii) Explain, in terms of bonds broken and bonds made, why this reaction is exothermic.
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