9701_w22_qp_43
A paper of Chemistry, 9701
Questions:
9
Year:
2022
Paper:
4
Variant:
3
Login to start this paper & get access to powerful tools
1
Potassiumchloride, KCl, and magnesiumchloride, MgCl 2, are both ionic solids. Table 1.1 energy change value / kJ mol–1 standard enthalpy change of solution, , of KCl +15 lattice energy, , of KCl –701 standard enthalpy change of hydration, , of K+ –322 standard enthalpy change of hydration, , of Cl – –364 standard enthalpy change of solution, , of MgCl 2 –155 lattice energy, , of MgCl 2–2493 Complete the energy cycle involving the enthalpy change of solution and the lattice energy of potassiumchloride, KCl, and the relevant enthalpy changes of hydration. Label your diagram. State symbols should be used. KCl  Use the data in Table1.1 to calculate the enthalpy change of hydration of magnesium ions, Mg2+. Show your working.  of magnesium ions, Mg2+ = kJ mol–1 Explain the reasons why the lattice energy of MgCl 2 is more exothermic than the lattice energy of KCl. Define the following terms. enthalpy change of atomisation first electron affinity Explain what is meant by entropy, S. Potassium chloride is very soluble in water at 20 °C. Explain the solubility of potassium chloride by reference to change in entropy, ∆S. Use the Gibbs equation and your answer to to predict whether potassiumchloride is more soluble in water at 20 °C or at 80 °C. Explain your answer. 
5. Chemical energetics  →  5.1. Enthalpy change, \(\Delta H\)
Open
2
Explain what is meant by the following terms: homogeneous catalyst heterogeneous catalyst  Iodide ions react with peroxydisulfate ions. 2I– + S2O8 2– → I2 + 2SO4 2– This reaction is slow, but it is catalysed by Fe2+ ions. Write two equations to explain how this reaction is catalysed by Fe2+ ions.  Suggest why the alternative route in the presence of Fe2+ ions has a lower activation energy than the route in the absence of a catalyst. Nitrogenmonoxide reacts with oxygen. 2NO+ O2→ 2NO2This reaction is second order with respect to nitrogenmonoxide and first order with respect to oxygen. Under certain conditions the value of the rate constant, k, is 8.60×106 mol–2dm6 s–1. Construct the rate equation for this reaction. rate =  Calculate the initial rate of the reaction under these conditions when the initial concentration of nitrogen monoxide is 7.20×10–4 mol dm–3 and the initial concentration of oxygen is 1.90×10–3 mol dm–3.  rate of reaction = mol dm–3 s–1 The drug cisplatin, Pt(NH3)2Cl 2, hydrolyses in water. Pt(NH3)2Cl 2 + H2O → [Pt(NH3)2Cl (H2O)]+ + Cl – The rate equation is shown. rate = k [Pt(NH3)2Cl 2] The value of k is 2.50×10–5 s–1 under certain conditions. This reaction has a constant half-life. Explain why this is the case. Use the information in this question to show that the half-life of this reaction is 2.77×104 s.  8.00×10–6 moles of Pt(NH3)2Cl 2 are added to 100 cm3 of water. Calculate the time taken for the concentration of Pt(NH3)2Cl 2 to fall to 2.50×10–6 mol dm–3.  time taken = s 
8. Reaction kinetics  →  8.1. Rate of reaction
8. Reaction kinetics  →  8.3. Homogeneous and heterogeneous catalysts
Open
3
Data should be selected from Table3.1 in order to answer some parts of this question. Table 3.1 electrode reaction E o / V Cl 2 + 2e– 2Cl – +1.36 2HOCl + 2H+ + 2e– Cl 2 + 2H2O +1.64 Cl O– + H2O + 2e– Cl – + 2OH– +0.89 Sn4+ + 2e– Sn2+ +0.15 Sn2+ + 2e– Sn –0.14 V2+ + 2e– V –1.20 V3+ + e– V2+ –0.26 VO2+ + 2H+ + e– V3+ + H2O +0.34 VO2 + + 2H+ + e– VO2+ + H2O +1.00 Standard electrode potentials are measured under standard conditions. Describe the standard conditions used in the Sn4+ / Sn2+ half-cell. Complete the diagram below to show how E o (Sn4+ / Sn2+) can be measured experimentally. Your diagram should be fully labelled to identify all apparatus and substances.  Equal volumes of 1.0 mol dm–3 Sn2+and 1.0 mol dm–3 Cl –are mixed. Use relevant E o values to explain whether a reaction occurs between these two ions. Equal volumes of 1.0 mol dm–3 of Sn2+and acidified 1.0 mol dm–3 VO2+are mixed. Write an equation for the reaction that takes place in the resulting mixture. A solution of SnCl 2is electrolysed for a measured time using a steady current. A mass of 2.95 g of tin metal is produced at the cathode. Al 2O3is electrolysed for the same time by the same current. Calculate the mass of aluminium metal produced at the cathode. Give your answer to three significant figures. Show your working.  mass of aluminium metal = g 
11. Group 17  →  11.4. The reactions of chlorine
2. Atoms, molecules and stoichiometry  →  2.4. Reacting masses and volumes (of solutions and gases)
Open
4
A sample of butanoic acid, CH3(CH2)2COOH, is shaken with a mixture of two immiscible solvents, ethoxyethane and water. The solvents form two layers. The butanoicacid is distributed between the two layers, its concentration in ethoxyethane being higher than its concentration in water. State what is meant by partition coefficient. The partition coefficient, Kpc, for butanoicacid between ethoxyethane and water is 3.50. A solution of 2.00 g of butanoic acid in 100 cm3 ethoxyethane is added to water. This mixture is left until there is no further change in the concentration of butanoicacid in either solvent. The mass of butanoicacid dissolved in the ethoxyethane layer is now 1.62 g. Calculate the volume of water used.  volume of water used = cm3 An aqueous solution of butanoicacid can be used to make a buffer solution. Define buffer solution. Suggest one organic compound, and one inorganic compound, that can be added to two different samples of aqueous butanoicacid to produce buffer solutions. organic compound inorganic compound  The solubility of aluminiumhydroxide, Al (OH)3, in water is 2.47×10–9 mol dm–3. Give the expression for the solubility product, Ksp, of aluminiumhydroxide. Ksp =  Calculate the numerical value of the Ksp of aluminiumhydroxide. Include the units of Ksp in your answer.  Ksp =  units =  
16. Hydroxy compounds  →  16.1. Alcohols
11. Group 17  →  11.4. The reactions of chlorine
7. Equilibria  →  7.1. Chemical equilibria: reversible reactions, dynamic equilibrium
Open
5
A transition element is a d-block element which forms one or more stable ions with incomplete d-orbitals. Two of the 3d orbitals are the 3dxy orbital and the 3dz2 orbital. Sketch the shapes of these two orbitals. 3dxy y z x 3dz2 z y x  The Ni2+ ion forms many different complexes. A solution containing the [Ni(H2O)6]2+ complex ion is green. When an excess of 1,2-diaminoethane, en, H2NCH2CH2NH2, is added, the colour of the solution changes to blue. This is due to the formation of the [Ni3]2+ complex ion. Explain why the two solutions are coloured, and why the colours are different. The [Ni3]2+ complex can exist as a mixture of two stereoisomers. Complete the three-dimensional diagram to show one of the stereoisomers. Each en ligand can be represented using N N . Ni  Name the geometry of the complex ion drawn in and the type of stereoisomerism shown by [Ni3]2+. geometry stereoisomerism shown  Iron(carbonate, FeCO3, and nickel(carbonate, NiCO3, both decompose when heated. FeCO3 decomposes at a lower temperature than NiCO3. Suggest a possible reason for this difference. Explain your answer. A is a pale green salt containing Fe2+ ions. A sample of 2.62 g of A is dissolved in water and the solution is made up to exactly 100 cm3 with water. 25.0 cm3 samples of this solution are placed in conical flasks and titrated against 0.0100 mol dm–3 acidified potassiummanganate(. The equation for the only reaction that occurs is shown. 5Fe2+ + MnO4 – + 8H+ → 5Fe3+ + Mn2+ + 4H2O The average titre value is 35.0 cm3 of 0.0100 mol dm–3 acidified potassiummanganate(. Describe the colour change that is seen in the conical flask at the end-point of this titration. The colour changes from to �������������������������������������������� . Calculate the percentage by mass of iron in A. [Ar: Fe, 55.8]  percentage by mass of iron = % 
11. Group 17  →  11.3. Some reactions of the halide ions
12. Nitrogen and sulfur  →  12.1. Nitrogen and sulfur
2. Atoms, molecules and stoichiometry  →  2.3. Formulas
Open
6
An aqueous solution of copper(sulfate is a blue colour due to the presence of [Cu(H2O)6]2+ complex ions. Write an equation for the reaction between [Cu(H2O)6]2+ ions and NaOH. Write an equation for the reaction between [Cu(H2O)6]2+ ions and an excess of conc.HCl. If an excess of ammonia is added to a solution of [Cu(H2O)6]2+ a deep blue solution containing [Cu(NH3)4(H2O)2]2+ complex ions is formed. There are two possible stereoisomers with the formula [Cu(NH3)4(H2O)2]2+. Complete the diagrams to show the two stereoisomers in the boxes below. isomer 1 isomer 2 Cu Cu  Use your answer in to deduce whether each of these isomers is polar or non-polar. polarity of isomer 1 polarity of isomer 2  The numerical value of the stability constant, Kstab, of the [Cu(NH3)4(H2O)2]2+ complex ion is 1.40×1013. Define stability constant. Compare the stabilities of the [Cu(H2O)6]2+ and [Cu(NH3)4(H2O)2]2+ complex ions. Explain your answer. Write an expression for the stability constant, Kstab, of the [Cu(NH3)4(H2O)2]2+ complex ion. State the units of the stability constant. Kstab =  units =  In a particular solution the concentration of the [Cu(NH3)4(H2O)2]2+ complex ion is 0.0074moldm–3 and the concentration of NH3 is 0.57 mol dm–3. Use your expression in and the Kstab value of 1.40×1013 to calculate the concentration of the [Cu(H2O)6]2+ complex ion in this solution.  concentration of [Cu(H2O)6]2+ = mol dm–3 Phenanthroline, C12H8N2, and ethanedioate ions, C2O4 2–, are bidentate ligands. Ruthenium(ions, Ru3+, form an octahedral complex with phenanthroline and chloride ions. The complex ion contains two phenanthroline molecules. Iron(ions, Fe3+, form an octahedral complex with ethanedioate ions only. Deduce the formula and charge of each of these complex ions. Ru3+ complex Fe3+ complex  
11. Group 17  →  11.3. Some reactions of the halide ions
2. Atoms, molecules and stoichiometry  →  2.3. Formulas
Open
7
The structure of compoundP is shown in Fig.7.1. H2N O O P Fig.7.1 P is optically active. Use an asterisk (*) to identify all chiral carbon atoms on the structure of P in Fig.7.1. Plane polarised light is passed through a pure sample of one enantiomer of P. This is then repeated with a pure sample of the other enantiomer of P. Describe the results of these two experiments, stating the similarities and differences of the results. P can be used to make compoundQ in a single step reaction. HN O O Q O Give the structural formula of the compound that is added to P to make Q and give the formula of the other product of this reaction. compound added to P other product  When an ester is treated with LiAl H4 in dry ether the ester linkage is cleaved by the addition of four hydrogen atoms and two alcohols are produced. Draw the structures of the compounds formed when Q is treated with an excess of LiAl H4 in dry ether.  Compare the relative basicities of compoundP, compoundQ and phenylamine. least basic most basic Explain your answer.  P can be used to make compoundR in a two-step reaction, shown in . two steps H2N O O H2N H2N OH O P R Identify the reagents and conditions used for the two steps of the reaction. step 1 step 2  Complete Table7.1 by drawing the structures of the organic products formed when R is treated separately with the reagents given. Table 7.1 reagent product HNO2at 4 °C an excess of Br2at room temperature  P can be used to produce compoundT. H2N OH O T In aqueous solution, T has a property called an isoelectric point. Explain what is meant by isoelectric point. T can polymerise under suitable conditions. No other monomer is involved in this reaction. Draw a section of the polymer chain formed that includes three T monomers. Identify the repeat unit on your diagram.  
13. An introduction to AS Level organic chemistry  →  13.1. Formulas, functional groups and the naming of organic compounds
14. Hydrocarbons  →  14.2. Alkenes
Open
8
Benzene, C6H6, is an aromatic molecule. State the C–C–C bond angle and the hybridisation shown by the carbon atoms in benzene. bond angle hybridisation  Benzene reacts with chloroethane in the presence of a catalyst. The reaction mechanism is called electrophilic substitution. The first step in the reaction is the generation of the +CH2CH3 electrophile. Write an equation for the reaction that generates this electrophile. Describe the mechanism for the reaction between benzene and the +CH2CH3 electrophile. Include all relevant curly arrows and charges. intermediate products +C H H C H H H → →  Chlorobenzene and chloroethane have different reactivities in nucleophilic substitution reactions. Identify a suitable reagent to illustrate this difference in reactivity. The reagent chosen should give visibly different results with chlorobenzene and chloroethane. Write equations to describe any reactions that occur.  Explain the difference in the reactivities of chlorobenzene and chloroethane in nucleophilic substitution reactions. 
15. Halogen compounds  →  15.1. Halogenoalkanes
14. Hydrocarbons  →  14.2. Alkenes
13. An introduction to AS Level organic chemistry  →  13.2. Characteristic organic reactions
Open
9
Gas-liquid chromatography involves a stationary phase and a mobile phase. Name, or describe in detail, a suitable substance that could be used for each phase. stationary mobile  A mixture of three organic compounds is separated by gas-liquid chromatography. The chromatogram obtained is shown in Fig.9.1. The amount of each substance is proportional to the area under its peak. retention time recorder response A C B Explain the meaning of retention time. Calculate the percentage of B in the mixture. Show your working.  percentage of B = % Complete Table9.1 to give the number of peaks in the carbon-13 NMR spectrum of each of the five isomers of C5H10O2 that has an ester group. Table 9.1 structural formula number of peaks CH3CH2CH2CO2CH3 CH3CH2CO2CH2CH3 CH3CO2CH2CH2CH3 (CH3)2CHCO2CH3 CH3CO2CH(CH3)2  State the number of peaks that would be seen in the proton (1H) NMR spectrum of methylbutanoate, CH3CH2CH2CO2CH3. Name all the splitting patterns seen in this spectrum. number of peaks splitting patterns  D and E are both esters with the molecular formula C5H10O2. Their proton (1H) NMR spectra are shown in Fig.9.2 and Fig.9.3. chemical shift, D chemical shift, E Table 9.2 environment of proton example typical chemical shift range, δ / ppm alkane –CH3, –CH2–, >CH– 0.9–1.7 alkyl next to C=O CH3–C=O, –CH2–C=O, >CH–C=O 2.2–3.0 alkyl next to aromatic ring CH3–Ar, –CH2–Ar, >CH–Ar 2.3–3.0 alkyl next to electronegative atom CH3–O, –CH2–O, –CH2–Cl 3.2–4.0 attached to alkene =CHR 4.5–6.0 Deduce the structures of the two esters D and E and draw their displayed formulae in the boxes below. D C5H10O2 E C5H10O2  The spectrum of D includes a quartet at δ4.1. Identify the protons responsible for this quartet on your structure in by labelling these protons with the letter F. Explain why this peak is split into a quartet.  The spectrum of E has a doublet at δ1.1. Identify the protons responsible for this doublet on your structure in by labelling these protons with the letter G. Explain why this peak has a chemical shift of 1.1.  
22. Analytical techniques  →  22.2. Mass spectrometry
Open