9701 Chemistry November 2025 Question Paper 22

1 Manganese, Mn, and its compounds are widely used in many chemical reactions.

(a) Mn is usually found as a single isotope, manganese-55.

(i) Determine the number of protons, neutrons and electrons in an atom of manganese-55.

number of protons neutrons electrons [1]

(ii) Define isotopes [1]

(iii) A sample of manganese from the Moon is found to contain manganese-53 in addition to manganese-55.

State the two pieces of information needed to determine the relative atomic mass, Ar , of manganese in this sample. 1 2 [2]

(b) The shorthand electronic configuration of manganese is [Ar] 3d5 4s2.

(i) Complete the full electronic configuration of manganese 3d5 4s2 [1]

(ii) Deduce the total number of unpaired electrons in an atom of manganese [1] , ,

(c) Manganese(IV) oxide reacts with methanal, CH2O, in acidic conditions to produce carbon dioxide. The movement of electrons to or from relevant species is shown in the following half-equations.

half-equation 1

CH2O + H2O CO2 + 4H+ + 4e–

half-equation 2

MnO2 + 4H+ + 2e– Mn2+ + 2H2O

(i) Identify the species that is reduced in half-equation 2. Explain your answer [1]

(ii) The oxidation state of carbon in methanal is 0.

Calculate the oxidation state of carbon in carbon dioxide [1]

(iii) Construct the ionic equation for the reaction of manganese(IV) oxide with methanal in acidic conditions [2]

[Total: 10] , ,

2 The Period 3 elements show trends in physical and chemical properties across the period.

(a) (i) Explain why the elements Na to Al are good electrical conductors [1]

(ii) Explain why the elements P, S and Cl do not conduct electricity [1]

(b) Fig. 2.1 shows the variation in melting point of the Period 3 elements Si to Cl. 1800 1600 1400 1200 1000 melting point / K 800 600 400 Si P S Cl 200 0 Fig. 2.1

The Period 3 elements Si to Cl are all non-metals.

Explain why there is a large difference between the melting point of Si and the melting points of P, S and Cl [2] , ,

(c) Table 2.1 gives some information about some Period 3 chlorides.

Row B refers to the pH of the solution that forms when the Period 3 chloride is added to water. Table 2.1 formula of Period 3 chloride NaCl MgCl 2 Al Cl 3 SiCl4 PCl 5 A oxidation number of element bonded to Cl B pH of solution 6.5 C bonding ionic D structure giant

Complete Table 2.1.

You may use the following abbreviations. I = ionic, C = covalent, M = metallic G = giant, S = simple

[4]

(d) (i) Write an equation for the formation of Al Cl 3 from its elements [1]

(ii) Write an equation for the formation of H3PO4 from PCl 5 [1]

(e) S2Cl2(l) reacts with Cl2(g) in a reversible reaction to form SCl2(l). Under certain conditions, a dynamic equilibrium is established. S2Cl2(l) + Cl2(g) 2SCl2(l) ΔH = – 41 kJ mol–1

(i) State what is meant by dynamic equilibrium [1]

(ii) Identify the condition necessary to establish dynamic equilibrium [1] , ,

(iii) S2Cl2(l) is yellow and SCl2(l) is red.

S2Cl2(l) + Cl2(g) 2SCl2(l) ΔH = – 41 kJ mol–1

State what is observed when the following changes are made to an equilibrium mixture of S2Cl2(l) and SCl2(l).

Explain your answers. • The equilibrium mixture is warmed gently. observation explanation • The overall pressure of the equilibrium mixture is increased. observation explanation [4]

(f) Aqueous MgCl 2 reacts with aqueous Na2CO3 to form a white precipitate. Upon heating, the white precipitate undergoes thermal decomposition.

(i) Construct an equation to show the reaction of aqueous MgCl 2 with aqueous Na2CO3. Use state symbols in your equation [2]

(ii) Identify the products of the thermal decomposition of the white precipitate [1]

(iii) State the trend in thermal stability of the Group 2 carbonates down the group [1]

[Total: 20] , ,

3 The alkanes are a homologous series of organic molecules. Alkanes are generally unreactive and are commonly used as fuels.

(a) Define homologous series [2]

(b) Give two reasons to explain the general unreactivity of alkanes. 1 2 [2]

(c) Alkanes with low relative molecular mass, Mr , are more useful than those found in heavier crude oil fractions.

Name the process that is used to obtain alkanes with low Mr from heavier crude oil fractions [1]

(d) Hexane, C6H14, has four structural isomers.

Fig. 3.1 shows hexane and two of its structural isomers. D C B A hexane Fig. 3.1

(i) Complete Fig. 3.1 by drawing structures for C and D, the other two structural isomers of hexane. [2]

(ii) A, B and hexane have different boiling points.

Arrange A, B and hexane in order of increasing boiling point.

Explain your answer.

lowest < < highest [3] , ,

(e) Hexane can be converted into compounds E and F at high temperature and pressure. Fig. 3.2 shows the reaction scheme involving hexane, E and F. reaction 3 ∆H2 reaction 2 ∆H1 = +215 kJ mol−1 reaction 1 E F Fig. 3.2

(i) Identify a suitable reagent for reaction 3 [1]

(ii) Use the data in Fig. 3.2 and in Table 3.1 to calculate the enthalpy change of reaction 2, ΔH2. Table 3.1 compound enthalpy change of formation, ∆Hf / kJ mol−1 −156 +48

ΔH2 = kJ mol–1 [2]

(iii) Write an equation for the complete combustion of hexane [1] [Total: 14] , ,

4 Fig. 4.1 shows how propane, C3H8, can be converted to propanoic acid, CH3CH2COOH. C3H8 CH3CH2CH2Cl CH3CH2CH2OH CH3CH2COOH reaction 1 reaction 2 reaction 3 Fig. 4.1

(a) Reaction 1 in Fig. 4.1 takes place in the presence of sunlight. C3H8 + Cl 2 CH3CH2CH2Cl + HCl

The reaction takes place via initiation, propagation and termination steps.

(i) Name the mechanism shown by reaction 1 [1]

(ii) Complete the mechanism for reaction 1.

Construct equations to describe the steps of the mechanism.

initiation Cl 2 → 2Cl• propagation 1 propagation 2 termination CH3CH2CH2Cl

[3]

(iii) Reaction 1 is initiated by the bond fission of Cl 2.

State the type of bond fission shown in the initiation step [1]

(iv) Compound Q is a by-product of reaction 1. H C C C H H H H Cl Q H Cl

Name Q [1] , ,

(v) The molecular formula of Q is C3H6Cl 2.

Identify the types of structural isomerism and stereoisomerism that a molecule with molecular formula C3H6Cl 2 can show. type of structural isomerism type of stereoisomerism [2]

(b) State the reagent and solvent required for reaction 2 [1]

(c) Reaction 3 takes place when CH3CH2CH2OH is heated under reflux with acidified potassium dichromate(VI) solution.

(i) State the colour change that takes place in the reaction mixture [1]

(ii) Construct an equation to represent reaction 3. Use [O] to represent an atom of oxygen from the oxidising agent [1] , ,

(d) CH3CH2COOH reacts with an unsaturated alcohol R to form unsaturated ester S.

(i) State the type of reaction that forms S [1]

(ii) The infrared spectrum of S is shown in Fig. 4.2. 100 50 4000 3000 2000 1500 wavenumber / cm−1 1000 500 transmittance / % 0 Fig. 4.2

Three absorptions in the infrared spectrum in Fig. 4.2 confirm that S is an ester and is unsaturated. • Write 1, 2 or 3 on Fig. 4.2 against each of these three absorptions. • Complete Table 4.1 to show which bond is responsible for each absorption that you have identified in Fig. 4.2. Table 4.1 absorption 1 2 3 bond responsible

[3] , , Table 4.2 bond functional groups containing the bond characteristic infrared absorption range (in wavenumbers) / cm–1 C–O hydroxy, ester 1040–1300 C=C aromatic compound, alkene 1500–1680 C=O amide carbonyl, carboxyl ester 1640–1690 1670–1740 1710–1750 C N nitrile 2200–2250 C–H alkane 2850–2950 N–H amine, amide 3300–3500 O–H carboxyl hydroxy 2500–3000 3200–3650

(iii) The mass spectrum of S shows the following peaks. Table 4.3 peak relative abundance M+ 4.7 [M+1]+ 0.31

Use Table 4.3 to calculate the number of carbon atoms in S. number of carbon atoms in S = [1]

[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 – , ,