9701 Chemistry November 2025 Question Paper 24

1 The Group 17 elements are oxidising agents.

(a) (i) Explain how the Group 17 elements act as oxidising agents [1]

(ii) Write an equation to show the reaction in which Cl 2 oxidises aluminium metal [1]

(iii) A student heats equal amounts of I2(g) and H2(g) in a sealed flask. The student leaves the contents to cool.

State what you would observe during the reaction [1]

(b) Cl 2 and Br2 can each react with NH3 to give N2 and a hydrogen halide, HX. 3X2 + 2NH3 N2 + 6HX

X = Cl or Br

The relative bond strengths of X–X and H–X determine the difference in enthalpy change of the two reactions.

(i) Describe and explain the difference in the X–X bond strengths of Cl 2 and Br2 [2]

(ii) Describe the relative thermal stabilities of HCl and HBr [1] , ,

(iii) Define enthalpy change of formation, ΔHf [2]

(iv) Table 1.1 gives data relevant to the reaction of Cl 2(g) with NH3(g). Table 1.1 compound enthalpy change of formation, ΔHf / kJ mol–1 NH3(g) – 46 HCl (g) –92

Use the data in Table 1.1 to calculate the enthalpy change of the reaction of Cl 2(g) with NH3(g).

enthalpy change of reaction = kJ mol–1 [2]

(v) I2 reacts with NH3 to form NI3.

Predict the shape of a molecule of NI3. Explain your answer. shape explanation [2] , ,

(c) Table 1.2 shows some information about reactions of NaCl , NaBr and NaI. Table 1.2 NaCl NaBr NaI observation with Ag+(aq) white precipitate type of reaction with concentrated H2SO4 acid–base acid–base, then redox acid–base, then redox observations with concentrated H2SO4 • black solid • yellow solid • effervescence

(i) Complete Table 1.2. [4]

(ii) Suggest an identity for the species that produces each observation in the reaction of NaI with concentrated H2SO4. black solid yellow solid effervescence [2]

(d) Table 1.3 gives some information about MgCl 2 and SiCl 4. Table 1.3 MgCl 2 SiCl 4 electrical conductivity when liquid conducts does not conduct observation when added to water dissolves vigorous reaction

(i) Explain the difference between the electrical conductivity of liquid MgCl 2 and of liquid SiCl 4. Refer to bonding and relevant particles in your answer [2]

(ii) Suggest the pH of the solutions that form when each chloride is added to water.

MgCl 2 SiCl 4 [2] [Total: 22] , ,

2 Aluminium oxide, Al 2O3, and phosphorus(V) oxide, P4O10, are both used as reagents and catalysts.

(a) The melting point of Al 2O3 is 2072 °C. The melting point of P4O10 is 340 °C.

Explain the difference in the melting points of these two compounds [3]

(b) A 5.00 dm3 sealed flask contains 0.400 mol of CO(g) and 0.800 mol of H2(g) and an Al 2O3 catalyst. The flask is heated to a temperature of 290 °C and allowed to reach equilibrium. Equation 1 shows the reaction.

equation 1 CO(g) + 2H2(g) CH3OH(g)

The equilibrium constant, Kc, of equation 1 is given. Kc = [CH3OH] [CO][H2]2

(i) State the units of Kc [1]

(ii) The equilibrium mixture contains 0.280 mol of CH3OH(g).

Calculate the value of Kc.

Give your answer to three significant figures.

value of Kc = [3]

(iii) State and explain the effect, if any, on the value of Kc when the overall pressure in the sealed flask is increased [1] , ,

(c) P4O10 catalyses the reversible reaction of CO with H2 to form CH3OH.

equation 1 CO(g) + 2H2(g) CH3OH(g)

P4O10 then acts as a dehydrating agent, causing CH3OH to form CH3OCH3.

(i) Explain how the presence of a catalyst affects a chemical reaction [1]

(ii) Construct an equation for the dehydration reaction of CH3OH to form CH3OCH3 [1]

(iii) Write an equation to show the reaction of P4O10 with an excess of water [1]

[Total: 11] , ,

3 Propan-2-ol, (CH3)2CHOH, is sometimes added to fuel to help it burn.

Fig. 3.1 shows some reactions of propan-2-ol. OH CH3CO2 – and CHI3 reaction 3 concentrated H2SO4 reaction 1 acidified K2Cr2O7 reaction 2 alkaline I2(aq) propan-2-ol L K Fig. 3.1

(a) (i) Draw the structure of organic compound K.

[1]

(ii) State an observation you would make in reaction 2 [1]

(iii) State the type of reaction that is shown in reaction 3 [1]

(iv) Complete Fig. 3.2 to show the pi (π) bond in L that is formed from orbital overlap. H H C C H3C H Fig. 3.2

[1] , ,

(b) Propan-2-ol reacts with sodium to produce (CH3)2CH–O – anions.

These anions react with 2-bromopropane to form compound N, as shown in Fig. 3.3. Br (CH3)2CH–O– O N Fig. 3.3

(i) Write an equation for the reaction of propan-2-ol with sodium [1]

(ii) The reaction of 2-bromopropane with (CH3)2CH–O – anions follows an SN1 mechanism.

Complete Fig. 3.4 to show this mechanism. Include charges, dipoles, lone pairs of electrons and curly arrows, as appropriate. (CH3)2CH–O– H3C C Br CH3 H H3C C CH3 CH3 H O C CH3 H Fig. 3.4

[3]

(iii) Suggest how the rate of the SN1 reaction would change, if at all, if 2-chloropropane were used instead of 2-bromopropane.

Explain your answer [2]

(iv) N is also added to petrol to make it burn more smoothly.

Construct an equation for the complete combustion of N, C6H14O. C6H14O [1]

[Total: 11] , ,

4 Compounds P and Q are structural isomers. P Q Fig. 4.1

(a) (i) Define structural isomerism [2]

(ii) P shows geometrical isomerism.

Draw the geometrical isomer of P. Explain why the two isomers are not identical. geometrical isomer of P explanation [2]

(iii) Both P and Q react with aqueous bromine.

Name the mechanism of this reaction [1]

(iv) Q is oxidised by hot concentrated acidified KMnO4(aq), forming two different organic products.

Construct an equation for this reaction. Use [O] to represent an atom of oxygen from the oxidising agent. (CH3)2C=CHCH3 [2] , ,

(v) Q reacts with HBr(g) to produce two structural isomers, R and S, as shown in Fig. 4.2. Q R HBr(g) Br and S Br Fig. 4.2

State and explain why isomer S is the major product of the reaction [2]

(vi) The mass spectrum of R shows peaks at m / e = 150 and m / e = 152.

Suggest structures for the ions responsible for these peaks. peak at m / e = 150

peak at m / e = 152

[2] , ,

(b) Fig. 4.3 shows a synthesis starting from T, a different isomer of R and S. Br T CN reaction 1 U COOH V reaction 2 HCl (aq) Fig. 4.3

(i) Identify the reagent and conditions for reaction 1 [1]

(ii) Reaction 2 is a hydrolysis reaction.

Construct an equation for reaction 2. (C2H5)2CHCN [1]

(iii) V reacts with propan-2-ol in the presence of a catalytic amount of H2SO4 to form organic compound W.

Complete Table 4.1 to give details of this reaction. Table 4.1 reaction of V with propan-2-ol type of reaction functional group formed molecular formula of organic product W

[3]

[Total: 16] , , Important values, constants and standards molar gas constant R = 8.31 J K–1 mol–1 Faraday constant F = 9.65 × 104 C mol–1 Avogadro constant L = 6.02 × 1023 mol–1 electronic charge e = –1.60 × 10–19 C molar volume of gas Vm = 22.4 dm3 mol–1 at s.t.p. (101 kPa and 273 K) Vm = 24.0 dm3 mol–1 at room conditions ionic product of water Kw = 1.00 × 10–14 mol2 dm–6 (at 298 K (25 °C)) specific heat capacity of water c = 4.18 kJ kg–1 K–1 (4.18 J g–1 K–1) , , Group The Periodic Table of Elements 1 H hydrogen 1.0 2 He helium 4.0 1 2 13 14 15 16 17 18 3 4 5 6 7 8 9 10 11 12 3 Li lithium 6.9 4 Be beryllium 9.0 atomic number atomic symbol Key name relative atomic mass 11 Na sodium 23.0 12 Mg magnesium 24.3 19 K potassium 39.1 20 Ca calcium 40.1 37 Rb rubidium 85.5 38 Sr strontium 87.6 55 Cs caesium 132.9 56 Ba barium 137.3 87 Fr francium – 88 Ra radium – 5 B boron 10.8 13 Al aluminium 27.0 31 Ga gallium 69.7 49 In indium 114.8 81 Tl thallium 204.4 6 C carbon 12.0 14 Si silicon 28.1 32 Ge germanium 72.6 50 Sn tin 118.7 82 Pb lead 207.2 22 Ti titanium 47.9 40 Zr zirconium 91.2 72 Hf hafnium 178.5 104 Rf rutherfordium – 23 V vanadium 50.9 41 Nb niobium 92.9 73 Ta tantalum 180.9 105 Db dubnium – 24 Cr chromium 52.0 42 Mo molybdenum 95.9 74 W tungsten 183.8 106 Sg seaborgium – 25 Mn manganese 54.9 43 Tc technetium – 75 Re rhenium 186.2 107 Bh bohrium – 26 Fe iron 55.8 44 Ru ruthenium 101.1 76 Os osmium 190.2 108 Hs hassium – 27 Co cobalt 58.9 45 Rh rhodium 102.9 77 Ir iridium 192.2 109 Mt meitnerium – 28 Ni nickel 58.7 46 Pd palladium 106.4 78 Pt platinum 195.1 110 Ds darmstadtium – 29 Cu copper 63.5 47 Ag silver 107.9 79 Au gold 197.0 111 Rg roentgenium – 30 Zn zinc 65.4 48 Cd cadmium 112.4 80 Hg mercury 200.6 112 Cn copernicium – 114 Fl flerovium – 116 Lv livermorium – 7 N nitrogen 14.0 15 P phosphorus 31.0 33 As arsenic 74.9 51 Sb antimony 121.8 83 Bi bismuth 209.0 8 O oxygen 16.0 16 S sulfur 32.1 34 Se selenium 79.0 52 Te tellurium 127.6 84 Po polonium – 9 F fluorine 19.0 17 Cl chlorine 35.5 35 Br bromine 79.9 53 I iodine 126.9 85 At astatine – 10 Ne neon 20.2 18 Ar argon 39.9 36 Kr krypton 83.8 54 Xe xenon 131.3 86 Rn radon – 113 Nh nihonium – 115 Mc moscovium – 117 Ts tennessine – 118 Og oganesson – 21 Sc scandium 45.0 39 Y yttrium 88.9 57–71 lanthanoids 89–103 actinoids 57 La lanthanum 138.9 89 Ac lanthanoids actinoids actinium – 58 Ce cerium 140.1 90 Th thorium 232.0 59 Pr praseodymium 140.9 91 Pa protactinium 231.0 60 Nd neodymium 144.2 92 U uranium 238.0 61 Pm promethium – 93 Np neptunium – 62 Sm samarium 150.4 94 Pu plutonium – 63 Eu europium 152.0 95 Am americium – 64 Gd gadolinium 157.3 96 Cm curium – 65 Tb terbium 158.9 97 Bk berkelium – 66 Dy dysprosium 162.5 98 Cf californium – 67 Ho holmium 164.9 99 Es einsteinium – 68 Er erbium 167.3 100 Fm fermium – 69 Tm thulium 168.9 101 Md mendelevium – 70 Yb ytterbium 173.1 102 No nobelium – 71 Lu lutetium 175.0 103 Lr lawrencium – , ,