科目：化学 Chemistry (9701)
年份：2025 夏季
试卷：Paper 44
总页数：22
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
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1. (a) (i) Describe the trend in the thermal stabilities of the carbonates of the Group 2 elements.
Explain your answer.
(ii) Copper(II) carbonate decomposes on heating in a similar way to the carbonates of Group 2.
Write an equation for the decomposition of copper(II) carbonate.
(b) (i) Complete the electrons in boxes diagram in Fig. 1.1 to show the electronic configuration of a copper(II) ion.
(ii) There are five different 3d orbitals.
Sketch the shape of a $3d_{z^2}$ orbital in Fig. 1.2.
(iii) Copper can form stable complexes in the +1 and +2 oxidation states.
Explain why transition elements have variable oxidation states.(c) (i) 1,2-diaminoethane, H$_2$NCH$_2$CH$_2$NH$_2$, en, can act as a bidentate ligand.
Explain what is meant by a bidentate ligand.
[2]
(ii) The complex [Cu(H$_2$O)$_2$(en)$_2]$^{2+} exists as stereoisomers.
Complete the three-dimensional diagrams in Fig. 1.3 to show the three different stereoisomers of [Cu(H$_2$O)$_�$(en)$_2]$^{2+}$.
The en ligand can be represented using
[3]
(iii) State the different types of stereoisomerism shown by [Cu(H$_2$O)$_₂$(en)$_₂]$^{2+}$.
[1](iv) Identify one isomer in (c)(ii) that is polar. Explain your answer.
isomer ..... [1]
(d) (i) The mineral ore cryolite, Na$_3$AlF$_6$, contains a single anion which is a complex ion.
Complete Table 1.1 to suggest the formula of the complex ion and to identify the ligand present in Na$_3$AlF$_6$.
Table 1.1
| complex ion in Na$_3$AlF$_6 $ | |
| :--- | :--- |
| ligand in Na$_3$AlF$_6 $_ | |
[1]
(ii) When a solution of Al$_2$O$_3$ in molten cryolite is electrolysed, aluminium metal is formed at the cathode. The equation is shown.
$$\text{Al}^{3+} + 3\text{e}^- \rightarrow \text{Al}$$
Calculate the maximum mass of aluminium produced when a current of 1.5A is passed through this solution for 30 minutes.
Give your answer to two significant figures.
mass of aluminium = ... g [4]
[Tot2 (a) Anhydrous barium chloride can be obtained from the hydrated salt, as shown in reaction 1.
$$\text{BaCl}_2 \cdot 2\text{H}_2\text{O(s)} + 2\text{SOCI}_2(\text{l}) \rightarrow \text{BaCl}_2(\text{s}) + 2\text{SO}_2(\text{g}) + 4\text{HC}l(\text{g})$$
(i) Describe one observation when reaction 1 is carried out.
[1]
(ii) Define the term entropy, $S$.
[1]
(iii) The entropy change, $\Delta S^\ominus$, for reaction 1 at $25^{\circ}\text{C}$ is $+768\text{JK}^{-1}\text{mol}^{-1}$.
Explain why $\Delta S^\ominus$ has a large positive value.
[1]
(iv) Table 2.1 shows the enthalpy changes of formation, $\Delta H_f^\ominus$, for the compounds in reaction 1.
| compound | $\Delta H_f^\ominus/\text{kJ mol}^{-1}$ |
| :--- | :--- |
| $\text{BaCl}_2(\text{ s })$ | $-859$ |
| $\text{BaCl}_2 \cd(b) When aqueous solutions of BaCl$_2$ and Na$_2$Cr$_2$O$_7$ are mixed, a yellow precipitate of BaCrO$_4$(s) is produced and an acidic solution remains. (i) Write the ionic equation for this reaction. [1] (ii) Explain why BaCrO$_4$(s) is coloured. [3] (c) Barium sulfate is the least soluble of the Group 2 sulfates. Explain the trend in the solubilities of the Group 2 sulfates. [3]
3 (a) Nickel(II) iodate(V), Ni(IO$_3$)$_2$, is sparingly soluble in water. The concentration of its saturated solution is $2.30 \times 10^{-2}$ mol dm$^{-3}$ at 298 K.
(i) Complete the expression for the solubility product, $K_{\text{sp}}$, of Ni(IO$_3$)$_2$. Include the units.
$$K_{\text{sp}} =$$
units = ..... [2]
(ii) Calculate the numerical value for $K_{\text{sp}}$ of Ni(IO$_3$)$_�$ at 298 K.
$$K_{\text{sp}} = ...$$ [1]
(b) An electrochemical cell is set up as shown in Fig. 3.1.
The relevant standard electrode potentials, $E^\ominus$, for this electrochemical cell are shown.
$$\text{IO}_3^-(\text{aq}) + 6\text{H}^+(\text{aq}) + 5\text{e}^- \rightleftharpoons \frac{1}{2}\text{I}_2(\text{aq}) + 3\text{H}_2\text{O}(\text{l})$$
$$E^\ominus = +1.19\text{V}$$
$$(iii) Complete Table 3.1 by placing one tick ($\checkmark$) to indicate how the $E_{\text{cell}}$ of this cell changes when a small amount of NiSO$_4$(aq) is added to the beaker containing Ni($IO_3$)$_2$(aq) and I$_2$(aq) in Fig. 3.1.
Explain your answer.
Table 3.1
| change in $E_{\text{cell}}$ |
|-------------------------|
| less positive | no change | more positive |
[2]
(c) In solution, iodic(V) acid, HIO$_3$, ionises as shown.
$$HIO_3(aq) \rightleftharpoons IO_3^-(aq) + H^+(aq)$$
The pH of a 1.0 mol dm$^{-3}$ solution of HIO$_3$ is 0.47.
(i) Calculate [H$^{+</sup>((aq))], in mol dm$^{-3}$, in a 1.0 mol dm$-$3$ solution of HIO$_3$.
$$[H^{+</sup>((aq))] = ... mol dm$^{-3}$ [1]
(ii) Use your answer from (c)(i) to calculate the equilibrium concentrations of HIO$_3$(aq) and IO$_3^(d) The Dushman reaction is the reaction between iodate(V) ions and iodide ions in acid solution.
$$\text{IO}_3^-(\text{aq}) + 5\text{I}^-(\text{aq}) + 6\text{H}^+(\text{aq}) \rightarrow 3\text{I}_2(\text{aq}) + 3\text{H}_2\text{O}(\text{l})$$
The rate equation for this reaction is shown.
$$\text{rate} = k [\text{IO}_3^-][\text{I}^-]^2[\text{H}^+]^2$$
The rate of this reaction is investigated in a buffer solution.
The initial concentrations are shown.
$$[\text{IO}_3^-] = 0.500 \text{ mol dm}^{-3}$$
$$[\text{I}^-] = 1.00 \times 10^{-3} \text{ mol dm}^{-3}$$
$$[\text{H}^+] = 1.00 \times10^{-2} \text{ mol dm}^{-2}$$
Under these conditions the initial rate of the reaction is $2.10 \times 10^{-2} \text{ mol } \text{dm}^{-3} \text{ s}^{-1}$.
(i) Define buffer solution.
[2]
(ii) Use theBLANK PAGE
4 Table 4.1 shows the structures of sections of three polymers, X, Y and Z. Each polymer is made from only one type of monomer. Table 4.1 polymer structure of section of polymer X Y Z (a) Complete Table 4.2 to state the type of polymerisation and draw the structure of the monomer for each polymer, X, Y and Z. Table 4.2 polymer type of polymerisation structure of monomer X Y Z
(b) Amino acids can act as monomers. State what is meant by the isoelectric point of an amino acid. (c) Electrophoresis can be used to separate and identify amino acids. Table 4.3 shows information about the three amino acids glycine, lysine and glutamic acid. | amino acid | structural formula of amino acid | isoelectric point | | :--- | :---: | :---: | | glycine (gly) | $H_2NCH_2COOH$ | 6.0 | | lysine (lys) | $H_2NCH(CH_2CH_2CH_2NH_2)COOH$ | 9.7 | | glutamic acid (glu) | $H_2NCH(Ch_2CH_2COOH)COOH$ | 3.2 | (i) A mixture containing these three amino acids is analysed in a buffer solution of pH 6.0. Draw and label **three** spots on Fig. 4.1 to indicate the predicted position of each of these amino acids, gly, lys and glu, after electrophoresis. Fig. 4.1 (ii) Electrophoresis is repea
5 A group of drugs known as statins are used to lower cholesterol in blood. A commonly used statin is atorvastatin.
**Fig. 5.1**
(a) Statins can break down in the acid found in the stomach.
(i) Draw a line through the bond in the atorvastatin structure in Fig. 5.1 that could be broken under acid conditions. [1]
(ii) By referring to the structure, explain why atorvastatin dissolves in water.
[1]
(iii) Complete the molecular formula of atorvastatin.
$$\text{C H}_{35} \text{N O F}$$
[1]
(iv) Atorvastatin contains chiral carbon atoms.
Circle all chiral carbon atoms in Fig. 5.1. [1]
(v) The synthetic preparation of atorvastatin requires the production of a single optical isomer.
Suggest why.
[1](b) (i) The proton ($^1\text{H}$) NMR spectrum of atorvastatin dissolved in CDCl$_3$ is recorded.
Use Table 5.1 to deduce the number of hydrogen atoms that could produce peaks in the region $\delta = 6.5–13.0 \text{ppm}$.
(ii) The proton ($^1\text{ H}$) NMR spectrum of atorvASTATIN dissolved in D$_2$O is recorded.
Predict the number of hydrogen atoms that would **not** show a peak in this spectrum.
Explain your answer.
[1]
| environment of proton | example | chemical shift range $\delta/\text{ppm}$ |
| :--- | :--- | :--- |
| alkane | $-CH_3, -CH_2-, >CH-$ | 0.9–1.7 |
| alkyl next to C=O | CH$_3$-C=O, -CH$_2$-C=O, >CH–C=O | 2.2–3.0 |
| alkyl next to aromatic ring | CH$_3$–Ar, -CH$_2$–Ar, >CH–Ar | 2.3–3.0 |
| alkyl next到 electronegative atom | CH$_3$–O, -CH$_2$–O, -CH$_2$−Cl | 3.2–4.0 BLANK PAGE
6 (a) A list of tests for different organic groups is given in Table 6.1. Complete Table 6.1 to identify an organic functional group, in aliphatic compounds, that produces a positive result in each test. Table 6.1 test sodium metal Na$_2$CO$_3$(aq) 2,4-DNPH I$_2$(aq) + OH$^-$(aq) warm with Fehling’s reagent Br$_2$(aq) [4]
(b) Lavandulol is an aliphatic organic compound and the major component of lavender oil. Fig. 6.1 shows a reaction scheme involving lavandulol, A.
$$\text{lavandulol}, \text{A} (\text{C}_{10}\text{H}_{18}\text{O})$$
$$\text{B} (\text{C}_{10}\\text{H}_{16}\text{O})$$
heat with concentrated acidified KMnO$_4$
$$\text{C} (\text{C}_6\text{H}_8\text{O}_5) + \text{D} (\text{C}_3\text{H}_6\text{O}) + \text{CO}_2$$
NaBH$_4$
$$\text{E} (\text{C}_6\text{ H}_{10}\text{O}_5)$$
$$\text{F} (\text{C}_6\text{,H}_8\text{O}_4)$$
heat with concentrated H$_2$SO$_4$
heat with concentrated acidified KMn O$_4$
$$\text{G} (\text{C}_4\text{H}_4\text{O}_5) + \text {H} (\text{C}_2\text{H}_4\text{O}_2)$$
Fig. 6.1Table 6.2 shows the results obtained when the tests in Table 6.1 are carried out on the eight organic compounds, A–H, in the reaction scheme in Fig. 6.1. | letter of compound | test | | :--- | :--- | | sodium metal | Na₂CO₃(aq) | | 2,4-DNPH | I₂(aq) + OH⁻(aq) | | warm with Fehling’s reagent | Br₂(aq) | | A | ✓ | | B | ✗ | | C | ✓ | | D | ✗ | | E | ✓ | | F | ✓ | | G | ✓ | | H | ✓ | (i) Deduce the functional group present in compound A using both the molecular formulae of A and B and the reaction of B with Fehling’s reagent. [1] (ii) Name the type of reaction that occurs in each of the following conversions. • A → B • C → E • E → F [3] (iii) Use the information in Table 6.2 and the molecular formulae to deduce structures for G and H. Draw your structures in Fig. 6.1. [2] (iv) Use
7 (a) State the relative acidities of benzoic acid, C$_6$H$_5$COOH, ethanol, CH$_3$CH$_2$OH, and phenol, C$_6$H$_5$OH, in aqueous solution. Explain your answer. most acidic least acidic (b) Draw the major products from the nitration of benzoic acid and phenol in the boxes in Fig. 7.1. The molecular formula for each major product is given in the boxes. major product from benzoic acid, C$_7$H$_5$NO$_4$ major product from phenol, C$_6$H$_五$NO$_3$ Fig. 7.1 (c) Ethanol reacts with propanoyl chloride, C$_2$H$_5$COCl, to form ester W. Fig. 7.2 (i) Give the systematic name for ester W. [1]
(ii) Complete the mechanism in Fig. 7.3 for the reaction between C$_2$H$_5$COCl and ethanol. R–OH represents ethanol. Include all relevant lone pairs of electrons, curly arrows, charges and partial charges. Fig. 7.3 [4] (iii) Name the mechanism for the reaction shown in Fig. 7.3. [1] [Total: 11]
8 (a) (i) Define lattice energy, $\Delta H_{\text{latt}}$.
[2]
(ii) Define enthalpy change of solution, $\Delta H_{\text{sol}}$.
[1]
(b) The enthalpy change of hydration can be represented by $\Delta H_{\text{hyd}}$.
Write the mathematical expression for the $\Delta H_{\text{sol}}$ of NaCl in terms of $\Delta H_{\text{latt}}(\text{NaCl})$, $\Delta H_{\text{hyd}}(\text{Na}^{+})$ and $\Delta H_{\text{hyd}}(\mathrm{Cl}^{-})$.
$$\Delta H_{\text{sol}}(\text{NaCl}) = \dots$$
[1]
(c) Complete the Born–Haber cycle in Fig. 8.1 for the ionic solid NaCl.
Include state symbols of relevant species.
Key
$\Delta H_{\text{i1}}$ first ionisation energy
$\Delta H_{\text{ea1}}$ first electron affinity
Fig. 8.1
[3](d) Predict which of the ions, $Cl^-$ or $NO_3^-$, has the more negative enthalpy change of hydration.
Explain your answer.
[Total: 9]
Important values, constants and standards
| | |
| :--- | :--- |
| molar gas constant | $R = 8.31 \text{ JK}^{-1}\text{mol}^{-1}$ |
| Faraday constant | $F = 9.65 \times 10^{4} \text{C mol}^{-1}$ |
| Avogadro constant | $L = 6.02 \times 10^{23} \text{mol}^{-1}$ |
| electronic charge | $e = -1.60 \times 10^{-19} \text{C}$ |
| molar volume of gas | $V_m = 22.4 \text{ dm}^3\text{mol}^{-1}$ at s.t.p. (101 kPa and 273 K)
$V_m = 24.0 \text{ dm}^3\text{ mol}^{-1}$ at room conditions |
| ionic product of water | $K_w = 1.00 \times 10^{-14} \text{mol}^2\text{dm}^{-6}$ (at 298 K (25 °C)) |
| specific heat capacity of water | $c = 4.18 \text{kJkg}^{-1}\text{K}^{-