科目：化学 Chemistry (9701)
年份：2017 春季
试卷：Paper 42
总页数：23
章节：19 Lattice energy, 20 Electrochemistry, 21 Further aspects of equilibria, 22 Reaction kinetics, 23 Entropy and Gibbs free energy, 24 Transition elements, 25 Benzene and its compounds, 26 Carboxylic acids and their derivatives, 27 Organic nitrogen compounds, 28 Polymerisation, 29 Organic synthesis, 30 Analytical chemistry
Answer all the questions in the spaces provided. 1. (a) (i) The mass spectrum of silicon is shown. Calculate the $A_r$ of silicon. Give your answer to two decimal places. $$A_r = \dots\dots\dots\dots\ldots\ldots\ldots\ldotp$$ (ii) Silicon forms a low boiling point chloride which reacts with water. Write an equation to show the reaction of the chloride with water. ... [1] (iii) Draw a three-dimensional diagram showing the shape of the chloride. Give the $Cl-Si-Cl$ bond angle. [2]
(iv) 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. [2] (b) 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. (i) Write an equation for the decomposition of the nitrate. [2] (ii) The oxide of element A has a high melting point. Suggest the structure and bonding present in the oxide of A. [1] [Total: 9]
2 (a) Complete the table using ticks ($\checkmark$) 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 | | | |
(b) The Born-Haber cycle for magnesium chloride is shown.
$$Mg^{2+}(g) + 2Cl^{-}(g) + 2e^-$$
(i) Explain why $\Delta H_4$ is greater than $\Delta H_3$.
[1]
(ii) What names are given to the enthalpy changes $\Delta H_6$ and $\Delta H_7$?
$\Delta H_6$ ..... [1]
$\Delta H_7$ ..... [1](c) Chlorine is in Group 17.
Suggest the trend in the first electron affinity of the elements in Group 17. Explain your answer.
[2]
(d) The equation for the formation of magnesium oxide from its elements is shown.
$$\text{Mg(s)} + \frac{1}{2}\text{O}_2(\text{g}) \rightarrow \text{MgO(s)} \quad \Delta H^\circ = -602\text{kJ mol}^{-1}$$
<table class="table table-bordered"><thead><tr><th>substance</th><th>S°/JK^{-1}mol^{-1}$</th></tr></thead><tbody><tr><td>Mg(s)</td><td>32.7</td></tr><tr><td>O₂(g)</td><td>205</td></tr><tr><td>MgO(s)</td><td>26.9</td></tr></tbody>
Use the equation and the data given in the table to calculate $\Delta G^\circ$ for the reaction at $25^{\circ}\text{C}$.
$\Delta G^\circ = \dots\dots\dots\dots\quad units \dots\dots\dots...$
[Total: 10]3 (a) The diagram shows the apparatus used to measure the standard electrode potential, $E^\circ$, of Fe$^{3+}$(aq)/Fe$^{2+}$(aq).
(i) Identify what the letters A to F represent.
A ... D ...
B ... E ...
C ... F ..... [3]
(ii) 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.
[1]
(b) In another experiment, an Fe$^{3+}$(aq)/ Fe$^{2+}$(aq) half-cell was connected to a Cu$^{2+}$(aq)/Cu(s) half-cell.
Determine the standard cell potential, $E^\circ_{\text{cell}}$, when these two half-cells are connected by a wire and the circuit is completed.
Use the Data Booklet to help you.
$$E^\circ_{\text{cell}} = \dots\dots\dots\dots\ V$$ [1](c) (i) The $E^e$ of Ni$^{2+}$(aq)/Ni(s) is –0.25 V.
State and explain how the electrode potential changes if the concentration of Ni$^{2+}$(aq) is decreased.
[1]
(ii) The $E^e$ of Cr$^{3+}$(aq)/Cr$^{2+}$(aq) is –0.41 V.
Calculate the electrode potential when [Cr$^{3+}$(aq)] is 0.60 mol dm$^{-3}$ and [Cr$^{2+}$(aq)] is 0.15 mol dm$^{-3}$. Use the Nernst equation.
$$E = E^e + \frac{0.059}{z} \log \frac{\text{oxidised species}}{\text{reduced species}}$$
$E = \dots\dots\dots\dots\mathrm{V}$ [2]
[Total: 8]4 (a) Chlorine dioxide undergoes the following reaction in aqueous solution.
$$2ClO_2 + 2OH^- \rightarrow ClO_2^- + ClO_3^- + H_2O$$
The initial rate of the reaction was measured at different initial concentrations of $ClO_2$ and $\text{OH}^-$. The table shows the results obtained.
| experiment | $[ClO_2]$ / mol dm$^{-3}$ | $[OH^-]$ / mol dm$^{-3}$ |
| :---: | :---: | :---: |
| 1 | $1.25 \times 10^{-2}$ | $1.30 \times 10^{-3}$ | $2.33 \times 10^{-4}$ |
| 2 | $2.50 \times 10^{-2}$ | $(\approx) 1.30 \times 10^{−3}$ | $9.34 \times 10^{−4}$ |
| 3 | $2.50 \times 10^{-2}$ | $2.60 \times 10^{−3}$$ | $1.87 \times 10^{−3}$$ |
(i) Use the data in the table to determine the rate equation, showing the order with respect to each reactant. Show your reasoning.
rate equation = ..... [3]
(ii) Calcu(ii) Complete the table using ticks ($\checkmark$) 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 | | |
(c) Some reactions are catalysed by one of the products of the reaction. This is called autocatalysis. An example of autocatalysis is the reaction between acidified manganate(VII) ions, MnO$_4^-$, and ethanedioic acid, $(CO_2H)_2$. Mn$^{2+}$ ions catalyse this reaction. The reaction is slow in the absence of a catalyst.
(i) Balance the equation for this reaction.
$$...MnO_4^- + ...H^+ + ...(CO_2H)_2 \rightarrow ...Mn^{(d) (i) Describe, with the aid of a reaction pathway diagram, the effect of a catalyst on a reversible reaction. Suggest why catalysts are used in industrial processes.
(ii) The reaction for the Haber process to produce ammonia is shown.
$$\text{N}_2(\text{g}) + 3\text{H}_2(\text{g}) \rightleftharpoons 2\text{NH}_3(\text{g}) \quad \Delta H^\circ = -92 \text{ kJ mol}^{-1}$$
At 500 °C, when pressure is measured in atmospheres, the numerical value of $K_p$ for this equilibrium is $1.45 \times 10^{-5}$.
• Write the expression for $K_p$ for this equilibrium.
$$K_p =$$
• Calculate the partial pressure of NH$_3$ at equilibrium at 500 °C, when the partial pressure of N$_2$ is 20 atm and that of H$_2$ is 60 atm.
$$p_{\text{NH}_3} = \dots\dots\dots\dots\mathrm{atm}$$
[Total: 17]5 (a) Compound H can be synthesised from benzene as shown.
(i) State the reagents and conditions needed for step 1.
reagents ...
conditions ... [2]
(ii) Step 2 takes place in the presence of chlorine gas.
State the conditions for this reaction.
... [1]
(iii) Draw the structure of intermediate G in the box. [1]
(iv) State the reagents and conditions needed for步3.
reagents ...
conditions ... [1]
(b) Write an equation to show how compound H, $C_{10}H_{13}NH_2$, behaves as a base.
... [1]
(c) Compare the relative basicities of ammonia, phenylamine and compound H. Explain your answer.
... [2]
[Total: 9]6 (a) (i) Draw the shape of one of the d orbitals. (ii) Complete the following electronic configurations. Ni 1s²2s²2p⁶3s²3p⁶ ... Ni³⁺ 1s²2s²2p₆3s²3p⁶ ... (b) (i) Complete the diagram to show how the presence of ligands around an isolated transition metal ion affects the energy of the d orbitals. energy degenerate d orbitals octahedral complex isolated transition metal ion tetrahedral complex (ii) Explain why transition metal complexes are coloured. [Cu(H₂O)₆]²⁺ is pale blue but [Cu(NH₃)₄(H₂O)₂]²⁺ is deep purple-blue. Suggest a reason for this.
(c) The diagram shows the visible spectrum of a solution of $[V(H_2O)_6]^{3+}$.
State and explain what colour the solution is.
colour of solution ..... [2]
(d) (i) In the presence of chloride ions, $[V(H_2O)_6]$$^{3+}$ reacts to form a mixture of isomeric octahedral complexes.
$$[V(H_2O)_6]^3+ + 2Cl^- \rightleftharpoons [V(H_2O)_4Cl_2]^+ + 2H_2O$$
Complete the three-dimensional diagrams to show the two isomers of $[V(H_2O)_4Cl_�]^+$.
(ii) State the type of isomerism shown by isomer 1 and isomer 2 in (i).
[1](e) (i) The complex $[V(H_2O)_6]^{3+}$ also reacts with ethane-1,2-diamine $(en)$, $H_2NCH_2CH_2NH_2$, to form a mixture of isomeric octahedral complexes.
$$[V(H_2O)_6]^3+ + 3en \rightleftharpoons [V(en)_3]^3+ + 6H_2O$$
Complete the three-dimensional diagrams to show the two isomers of $[V(en)_3]^{3+}$.
You may use $\text{N}\text{N}$ to represent $en$.
[2]
(ii) State the type of isomerism shown by isomer 1 and isomer 2 in (i).
... [1](f) The reaction of $[\text{Ni}(\text{H}_2\text{O})_6]^{2+}$ with aqueous ammonia produces the complex $[\text{Ni}(\text{NH}_3)_6]^{2+}$.
$$[\text{Ni}(\text{H}_�\text{O})_6]^{2+(aq)} + 6\text{NH}_3(aq) \rightleftharpoons [\text{Ni}(\text{NH}_3)]^{2+(aq)} + 6\text{\text{H}_2\text{O}(I)}$$
(i) Write the expression for $K_{\text{stab}}$ for $[\text{Ni}(\text{NH}_{3})_{6}]^{2+}$.
$$K_{\text{stab}} =$$
[1]
(ii) $[\text{Ni}(\text{H}_{2}\text{O})_6]^{2+}$, also reacts with en to form $[\text{Ni}(en)_3]^{2+}$. The values of the stability constants for the two complexes are shown.
$$K_{\text{stab}} [\text{Ni}(\text{NH}_{3 })_6]^{2+} = 4.8 \times 10^7 \text{mol}^{-6} \text{dm}^ {18}$$
$$K_{\text{stab}} [\text{Ni}(en)_3]^{2 +}=2.0 \times 10^{18} \text{mol}^{-3} \text{dm}^9$$
A solution contai7 The compound *Advantame* is a sweetener that tastes approximately 25,000 times sweeter than sucrose. (a) *Advantame* is optically active. On the diagram of *Advantame*, circle all the chiral carbon atoms. [1] (b) The decomposition of *Advantame* produces three molecules, J, K and L. The RO– group in *Advantame* is unreactive. (i) Suggest possible reagents and conditions for this decomposition. [1] (ii) Name the type of reaction occurring. [1] (iii) Draw the structure of L in the box above. [1]
(c) (i) Aqueous bromine was added dropwise to a solution of J until the bromine was in excess.
State what you would observe.
[1]
(ii) J has the molecular formula $C_{14}H_{19}O_6N$.
Use this formula to write an equation for the reaction of excess aqueous sodium hydroxide with one mole of J.
[2]
(d) (i) State what you would observe when an excess of aqueous bromine is added to a solution of K.
[1]
(ii) K can be polymerised.
Draw the structure of the polymer showing two repeat units. The linkage between the monomer units should be fully displayed.
[2](e) Use the Data Booklet to help you answer this question. The carbon-13 NMR spectrum of K was recorded. (i) State how many different carbon environments are present in K. [1] (ii) The chemical shifts, $\delta$, due to two of the carbon atoms x and y present in K are given in the table. | carbon atom | $\delta$/ppm | | :--- | :--- | | x | 130 | | y | 170 | On the structure of K, circle and label two carbon atoms which could correspond to x and y. [Total: 12]
Question 8 starts on the next page.
8 The root of the ginger plant contains compounds with medicinal and flavouring properties. Three of the more important compounds are gingerol, shogaol and zingerone. (a) The structure of gingerol is shown. The CH$_3$O– group in gingerol is unreactive. Gingerol reacts with acidified potassium dichromate(VI). State the type of reaction and the functional group change which occurs during this reaction. type of reaction ..... functional group change from ... to ..... [1] (b) The structure of shogaol is shown. (i) State the type of reaction needed to convert gingerol into shogaol. [1] (ii) State the reagents and conditions needed to convert gingerol into shogaOL. reagents ..... conditions ..... [1]
(iii) Shogaol reacts with hot, concentrated acidified manganate(VII) ions to form two organic products, Q and R. Draw the structures of Q and R. (c) Zingerone is formed from gingerol. Some reactions of zingerone are shown. Complete the table to identify the functional groups in zingerone.
9 This question is about compound $T$, $C_xH_yO_z$. (a) 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. (i) Calculate $x$, the number of carbon atoms present in $T$. $$x = \dots\dots\dots\dots\ldots\ldots\ldots\ldotp$$ (ii) Deduce the molecular formula of $T$. [1] (iii) The mass spectrum has a peak at $m/e = 119$. Identify the fragment lost from $T$ to produce this peak. [1]
(b) The infra-red spectrum of T is shown. Identify the type of bond responsible for each of the peaks V and W. Use the Data Booklet to help you. V ... W ... [1] (c) The proton NMR spectrum of T in CDCl$_3$ is shown. (i) Complete the table for the proton NMR spectrum of T. Use the Data Booklet to help you. | $\delta$/ppm | type of proton | | :--- | :--- | | 3.9 | | | 7.2–7.9 | |
(ii) The peak at $\delta = 2.4$ ppm is due to a proton attached to a saturated carbon atom. State the two possible types of proton. 1. ... 2. ... [1] (iii) Adding D$_2$O to T does not change its proton NMR spectrum. What does this tell you about the functional groups present in T? ... [1] (d) Use the information to draw two possible structures of T which are functional group isomers of each other. [2] [Total: 10]