9701_m17_qp_42
A paper of Chemistry, 9701
Questions:
9
Year:
2017
Paper:
4
Variant:
2
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1
The mass spectrum of silicon is shown. 1.0 0.5 0.047 0.031 0.922 m / e relative intensity Calculate the Ar of silicon. Give your answer to two decimal places. Ar = Silicon forms a low boiling point chloride which reacts with water. Write an equation to show the reaction of the chloride with water. Draw a three-dimensional diagram showing the shape of the chloride. Give the Cl – Si – Cl bond angle. Silicon reacts with oxygen to form a high melting point oxide. ● Suggest the formula of the oxide. ● Suggest, in terms of structure, why the oxide has a high melting point whereas the chloride has a low boiling point. Element A is in the same period as silicon. Element A reacts with dilute nitric acid to form a nitrate. This nitrate decomposes on heating to form an oxide. Write an equation for the decomposition of the nitrate. The oxide of element A has a high melting point. Suggest the structure and bonding present in the oxide of A.
9. The Periodic Table: chemical periodicity  →  9.2. Periodicity of chemical properties of the elements in Period 3
9. The Periodic Table: chemical periodicity  →  9.1. Periodicity of physical properties of the elements in Period 3
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Complete the table using ticks () to indicate whether the sign of each type of energy change, under standard conditions, is always positive, always negative or could be either positive or negative. energy change always positive always negative either positive or negative electron affinity enthalpy change of atomisation ionisation energy lattice energy The Born-Haber cycle for magnesium chloride is shown. Mg2++ 2Cl + 2e– Mg++ 2Cl + e– Mg2++ 2Cl –Mg+ 2Cl Mg+ Cl 2Mg+ Cl 2MgCl 2ΔH4 ΔH5 ΔH3 ΔH2 ΔH1 ΔH7 ∆H6 Explain why ΔH4 is greater than ΔH3. What names are given to the enthalpy changes ΔH6 and ΔH7? ΔH6 ΔH7 Chlorine is in Group 17. Suggest the trend in the first electron affinity of the elements in Group17. Explain your answer. The equation for the formation of magnesium oxide from its elements is shown. Mg+ 1 2O2MgOΔH o = – 602 kJ mol–1 substance S o / J K–1 mol–1 Mg32.7 O2205 MgO26.9 Use the equation and the data given in the table to calculate ΔG o for the reaction at 25 °C. ΔG o = units
5. Chemical energetics  →  5.1. Enthalpy change, \(\Delta H\)
9. The Periodic Table: chemical periodicity  →  9.2. Periodicity of chemical properties of the elements in Period 3
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The diagram shows the apparatus used to measure the standard electrode potential, E o, of Fe3+/ Fe2+. E F C A B V D Identify what the letters A to F represent. A D B E C F Label the diagram to show ● which is the positive electrode, ● the direction of electron flow in the external circuit. Use the Data Booklet to help you. In another experiment, an Fe3+/ Fe2+half-cell was connected to a Cu2+/ Cuhalf-cell. Determine the standard cell potential, , when these two half-cells are connected by a wire and the circuit is completed. Use the Data Booklet to help you. = V The E o of Ni2+/ Niis –0.25 V. State and explain how the electrode potential changes if the concentration of Ni2+is decreased. The E o of Cr3+/ Cr2+is –0.41 V. Calculate the electrode potential when [Cr3+] is 0.60 mol dm–3 and [Cr2+] is 0.15 mol dm–3. Use the Nernst equation. E = E o + 0.059 log [oxidised species] z [reduced species] E = V
6. Electrochemistry  →  6.1. Redox processes: electron transfer and changes in oxidation number (oxidation state)
1. Atomic structure  →  1.3. Electrons, energy levels and atomic orbitals
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Chlorine dioxide undergoes the following reaction in aqueous solution. 2Cl O2 + 2OH– Cl O2 – + Cl O3 – + H2O The initial rate of the reaction was measured at different initial concentrations of Cl O2 and OH–. The table shows the results obtained. experiment [Cl O2] / mol dm–3 [OH–] / mol dm–3 initial rate / mol dm–3 s–1 1.25 × 10–2 1.30 × 10–3 2.33 × 10–4 2.50 × 10–2 1.30 × 10–3 9.34 × 10–4 2.50 × 10–2 2.60 × 10–3 1.87 × 10–3 Use the data in the table to determine the rate equation, showing the order with respect to each reactant. Show your reasoning. rate equation = Calculate the value of the rate constant, k, using the data from experiment 2. State its units. k = units Explain the difference between heterogeneous and homogeneous catalysts. Complete the table using ticks () to indicate whether the catalyst used in the reaction is heterogeneous or homogeneous. catalysed reaction heterogeneous homogeneous manufacture of ammonia in the Haber process removal of nitrogen oxides from car exhausts oxidation of sulfur dioxide in the atmosphere Some reactions are catalysed by one of the products of the reaction. This is called autocatalysis. An example of autocatalysis is the reaction between acidifiedmanganate(ions, MnO4 –, and ethanedioicacid, (CO2H)2. Mn2+ ions catalyse this reaction. The reaction is slow in the absence of a catalyst. Balance the equation for this reaction. MnO4 – + H+ + (CO2H)2 Mn2+ + CO2 + H2O The graph shown is a concentration-time graph for a typical reaction. concentration of reactant time On the axes below, sketch the curve you would expect for the autocatalysed reaction in . concentration of MnO4 – time Describe, with the aid of a reaction pathway diagram, the effect of a catalyst on a reversible reaction. Suggest why catalysts are used in industrial processes. The reaction for the Haber process to produce ammonia is shown. N2+ 3H22NH3ΔH o = –92 kJ mol–1 At 500 °C, when pressure is measured in atmospheres, the numerical value of Kp for this equilibrium is 1.45 × 10–5. ● Write the expression for Kp for this equilibrium. Kp = ● Calculate the partial pressure of NH3 at equilibrium at 500 °C, when the partial pressure of N2 is 20atm and that of H2 is 60atm. pNH3 = atm
8. Reaction kinetics  →  8.1. Rate of reaction
11. Group 17  →  11.4. The reactions of chlorine
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Compound H can be synthesised from benzene as shown. step 1 step 3 step 2 Cl 2intermediate G compound H NH2 State the reagents and conditions needed for step 1. reagents conditions Step2 takes place in the presence of chlorine gas. State the conditions for this reaction. Draw the structure of intermediate G in the box. State the reagents and conditions needed for step 3. reagents conditions Write an equation to show how compound H, C10H13NH2, behaves as a base. Compare the relative basicities of ammonia, phenylamine and compound H. Explain your answer.
21. Organic synthesis  →  21.1. Organic synthesis
14. Hydrocarbons  →  14.1. Alkanes
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Draw the shape of one of the d orbitals. Complete the following electronic configurations. Ni 1s22s22p63s23p6 Ni3+ 1s22s22p63s23p6 Complete the diagram to show how the presence of ligands around an isolated transition metal ion affects the energy of the dorbitals. energy octahedral complex isolated transition metal ion degenerate d orbitals tetrahedral complex Explain why transition metal complexes are coloured. [Cu(H2O)6]2+ is pale blue but [Cu(NH3)4(H2O)2]2+ is deep purple-blue. Suggest a reason for this. The diagram shows the visible spectrum of a solution of [V(H2O)6]3+. absorption wavelength / nm 350 400 450 500 550 600 650 700 blue green red State and explain what colour the solution is. colour of solution explanation In the presence of chloride ions, [V(H2O)6]3+ reacts to form a mixture of isomeric octahedral complexes. [V(H2O)6]3+ + 2Cl – [V(H2O)4Cl 2]+ + 2H2O Complete the three-dimensional diagrams to show the two isomers of [V(H2O)4Cl 2]+. V isomer 1 V isomer 2 State the type of isomerism shown by isomer 1 and isomer 2 in . The complex [V(H2O)6]3+ also reacts with ethane-1,2-diamine , H2NCH2CH2NH2, to form a mixture of isomeric octahedral complexes. [V(H2O)6]3+ + 3en [V3]3+ + 6H2O Complete the three-dimensional diagrams to show the two isomers of [V3]3+. You may use N N to represent en. V isomer 1 V isomer 2 State the type of isomerism shown by isomer1 and isomer2 in . The reaction of [Ni(H2O)6]2+ with aqueous ammonia produces the complex [Ni(NH3)6]2+. [Ni(H2O)6]2++ 6NH3[Ni(NH3)6]2++ 6H2OWrite the expression for Kstab for [Ni(NH3)6]2+. Kstab = [Ni(H2O)6]2+ also reacts with en to form [Ni3]2+. The values of the stability constants for the two complexes are shown. Kstab [Ni(NH3)6]2+ = 4.8 × 107 mol–6 dm18 Kstab [Ni3]2+ = 2.0 × 1018 mol–3 dm9 A solution containing equal numbers of moles of ammonia and en is added to [Ni(H2O)6]2+. State which complex is produced in the larger amount. Explain your answer. Adding a limited amount of en to [Ni(H2O)6]2+ forms the complex [Ni(H2O)22]2+. Suggest the number of possible stereoisomers of [Ni(H2O)22]2+. Explain your answer. You are advised to include three-dimensional diagrams in your answer.
1. Atomic structure  →  1.3. Electrons, energy levels and atomic orbitals
11. Group 17  →  11.1. Physical properties of the Group 17 elements
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The compound Advantame is a sweetener that tastes approximately 25 000 times sweeter than sucrose. RO HO OH CH3 H N O O O O Advantame N H Advantame is optically active. On the diagram of Advantame, circle all the chiral carbon atoms. The decomposition of Advantame produces three molecules, J, K and L. The RO–group in Advantame is unreactive. HO OH OH H N O O + O OH H2N J K + L RO Suggest possible reagents and conditions for this decomposition. Name the type of reaction occurring. Draw the structure of L in the box above. Aqueous bromine was added dropwise to a solution of J until the bromine was in excess. State what you would observe. J has the molecular formula C14H19O6N. Use this formula to write an equation for the reaction of excess aqueous sodiumhydroxide with one mole of J. State what you would observe when an excess of aqueous bromine is added to a solution of K. K can be polymerised. Draw the structure of the polymer showing two repeat units. The linkage between the monomer units should be fully displayed. Use the Data Booklet to help you answer this question. The carbon-13 NMR spectrum of K was recorded. O K OH H2N State how many different carbon environments are present in K. The chemical shifts, δ, due to two of the carbon atoms x and y present in K are given in the table. carbon atom δ / ppm x y On the structure of K, circle and label two carbon atoms which could correspond to x and y.
14. Hydrocarbons  →  14.2. Alkenes
15. Halogen compounds  →  15.1. Halogenoalkanes
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The root of the ginger plant contains compounds with medicinal and flavouring properties. Three of the more important compounds are gingerol, shogaol and zingerone. The structure of gingerol is shown. The CH3O– group in gingerol is unreactive. HO CH3O O OH gingerol Gingerol reacts with acidified potassium dichromate(. State the type of reaction and the functional group change which occurs during this reaction. type of reaction functional group change from to The structure of shogaol is shown. HO O CH3O shogaol State the type of reaction needed to convert gingerol into shogaol. State the reagents and conditions needed to convert gingerol into shogaol. reagents conditions Shogaol reacts with hot, concentrated acidified manganate(ions to form two organic products, Q and R. Draw the structures of Q and R. Q R Zingerone is formed from gingerol. Some reactions of zingerone are shown. Complete the table to identify the functional groups in zingerone. reagent and conditions observation functional group in zingerone indicated by the observation benzenediazonium chloride, 5 °C, alkaline solution red ppt. 2,4-dinitrophenylhydrazine orange ppt. warm with Tollens’ reagent no change
16. Hydroxy compounds  →  16.1. Alcohols
17. Carbonyl compounds  →  17.1. Aldehydes and ketones
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This question is about compound T, CxHyOz. Part of the mass spectrum of T is shown. The peak heights of the M and M+1 peaks are 33.9 and 3.4 respectively. relative intensity m / e Calculate x, the number of carbon atoms present in T. x = Deduce the molecular formula of T. The mass spectrum has a peak at m / e = 119. Identify the fragment lost from T to produce this peak. The infra-red spectrum of T is shown. transmittance wavenumber / cm–1 V W Identify the type of bond responsible for each of the peaks V and W. Use the Data Booklet to help you. V W The proton NMR spectrum of T in CDCl 3 is shown. δ / ppm 3H 3H 4H Complete the table for the proton NMR spectrum of T. Use the Data Booklet to help you. δ / ppm type of proton 3.9 7.2–7.9 The peak at δ=2.4 ppm is due to a proton attached to a saturated carbon atom. State the two possible types of proton. 1. 2. Adding D2O to T does not change its proton NMR spectrum. What does this tell you about the functional groups present in T? Use the information to draw two possible structures of T which are functional group isomers of each other.
22. Analytical techniques  →  22.2. Mass spectrometry
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