科目：化学 Chemistry (9701)
年份：2025 夏季
试卷：Paper 41
总页数：21
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, 30 Analytical chemistry
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1 Both calcium carbonate, CaCO$_3$, and barium carbonate, BaCO$_3$, decompose when heated to form the metal oxide and a gas. (a) Write an equation for the thermal decomposition of CaCO$_3$. [1] (b) State which of CaCO$_3$ and BaCO$_3$ decomposes at a lower temperature. Explain your answer. The compound that decomposes at a lower temperature is explanation [2] (c) Calcium oxide, CaO, reacts with water to form compound A. Barium oxide, BaO, reacts with water to form compound B. (i) Identify A. [1] (ii) Explain why A is less soluble than B. [3] Total: 7
2 Three experiments are carried out to investigate the reaction of nitrogen oxide, NO, with chlorine.
$$2\text{NO} + \text{Cl}_2 \rightarrow 2\text{NOCI}$$
The rate equation for this reaction is shown.
$$\text{rate} = k[\text{NO}]^2[\text{Cl}_2]$$
(a) Under the conditions used in experiments 1 and 2, the value of $k$ is 26.4.
(i) The rate of the reaction is measured in mol dm$^{-3}$ s$^{-1}$. State the units of $k$.
units of $k$ = ..... [1]
(ii) In experiment 1, the initial concentrations of NO and $\text{Cl}_2$ are equal.
The initial rate of the reaction in experiment 1 is $2.57 \times 10^{-6}\text{mol dm}^{-3}\text{s}^{-1}$.
Calculate the initial concentration of NO.
Show your working.
initial concentration of NO = ..... mol dm$^{-3}$ [2]
(iii) In experiment 2, the initial co(b) Experiment 3 uses a large excess of NO.
The initial concentration of $Cl_2$ is $2.00 \times 10^{-4} \text{ mol dm}^{-3}$.
(i) The graph of $[Cl_2]$ against time shows that the reaction has a constant half-life, $t_{1/2}$.
Explain this observation.
(ii) Under the conditions used in experiment 3, the value of the rate constant is 105.6.
Show that $t_{1/2}$ of $[Cl_2]$ is $6.56 \times 10^{-3} \text{ s}$ under these conditions.
(iii) Calculate the time taken, in s, for $[Cl_2]$ to fall to $1.25 \times 10^{-5} \text{ mol dm}^{-2}$ in experiment 3.
time = ..... s [1]
(c) Sulfur dioxide, $SO_2$, reacts very slowly with oxygen in the atmosphere, forming sulfur trioxide, $SO_3$. This reaction is much faster in the presence of NO.
Explain the role of NO in this process.
Include chemical eq3 (a) Chromium(III) hydroxide, Cr(OH)$_3$, is only slightly soluble in water. The value of the solubility product, $K_{sp}$, of Cr(OH)$_3$ is $1.0 \times 10^{-33}$ at 298 K.
(i) Complete the expression for $K_{sp}$ of Cr(OH)$_3$. Include the units.
$$K_{sp} =$$
units = ..... [2]
(ii) Calculate the solubility, in g dm$^{-3}$, of Cr(OH)$_3$ in pure water at 298 K.
Show your working.
solubility = ..... g dm$^{-3}$ [3]
(iii) Cr(OH)$_3$ is less soluble in 0.100 mol dm$^{-3}$ NaOH than it is in pure water.
Explain this observation.
[1]
(b) The value of the acid dissociation constant, $K_a$, of butanoic acid, CH$_3$CH$_2$CH$_2$COOH, is $1.51 \times 10^{-5}$ at 298 K.
(i）Calculate the pH of 0.100 mol dm$-^3$ CH$_3$CH$_2$CH $_2$COOH at 298 K.
Show your工作。
pH = ..... [2]
(ii) Calculate th(iii) 5.00 cm$^3$ of $0.100\text{ mol}\text{dm}^{-3}$ NaOH is added to 10.00 cm$^3$ of 0.100\text{ mol}\mathrm{dm}^{-3}$ $\mathrm{CH}_3\mathrm{CH}_2\mathrm{CH}_2\mathrm{COOH}$.
Calculate the pH of the resulting solution.
Show your working.
$$\mathrm{pH} = \dots\dots\dots\dots\ldots\ldots\ldots\ldotdot\ldotdot\ldotdot\LDots$$
(c) 80.0 cm$^3$ of an aqueous solution containing 0.704 g of $\mathrm{CH}_3\mathrm{ CH}_2\mathrm{CH}_2\mathbf{COOH}$ is shaken with 100 cm$^3$ of benzene, $\mathrm{C}_6\mathrm{H}_6$.
There is 0.556 g of $\mathrm{CH}_3\mathbf{CH}_2\mathrm{CH}_�\mathbf{COOH}$ in the 100 cm$^3$ OF $\mathrm{C}_6\mathrm{ H}_6$ at equilibrium.
Calculate the partition coefficient, $K_{\mathrm{pc}}$, of $\mathrm{CH}_3\mathrm {CH}_2\mathrm{CH}_2\text{COOH}$ between $\mathrm{C}_6\mathrm{,HTable 4.1 gives the enthalpy changes of hydration, $\Delta H_{\text{hyd}}$, of three ions, $F^{-}$, $K^{+}$ and $Ca^{2+}$.
| ion | $\Delta H_{\text{hyd}} / \text{kJ mol}^{-1}$ |
| :--- | :---:|
| $F^{-}$ | –506 |
| $K^{+}$ | –322 |
| $Ca^{2+}$ | –1650 |
(a) (i) Define enthalpy change of hydration.
[1]
(ii) Explain the relative magnitudes of the enthalpy changes of hydration of $K^{+}$ and $Ca^{ 2+}$.
[2]
(iii) Define lattice energy.
[1]
(iv) The lattice energy, $\Delta H_{\text{latt}}$, of calcium fluoride, $CaF_{2}$, is –2602 kJ mol$^{-1}$.
Calculate the enthalpy change of solution, $\Delta H_{\text{sol}}$, in kJ mol$^{-1}$, of $CaF_{2}$.
$\Delta H_{\text{sol}}$ of $CaF_{2} = \dots\dots\dots\dots\mathrm{kJ mol}^{-1}$ [2](b) The formation of CaF$_2$ at 298 K is shown.
$$\text{Ca(s)} + \text{F}_2(\text{g}) \rightarrow \text{CaF}_2(\text{s}) \quad \Delta H^\circ = -1214 \text{ kJ mol}^{-1}$$
$$\Delta G^\circ = -1162 \text{ kJ mol}^{-1}$$
Calculate the entropy change, $\Delta S^\circ$, in JK$^{-1}$mol$^{-1}$, for this reaction.
$\Delta S^\circ = \dots\dots\dots\dots\ldots\ldots\ldots\ldotting\ldots\ldots\ldots\text{JK}^{-1}\text{mol}^{-1}$ [2]
[Total: 8]5 Copper is a transition element.
(a) (i) Complete the electronic configurations of a Cu$^+$ ion and a Cu$^{2+}$ ion.
Cu$^+$ ion: [Ar]
Cu$^{2+}$ ion: [Ar]
[1]
(ii) Explain why transition elements have variable oxidation states.
[1]
(b) Aqueous copper(II) sulfate, CuSO$_4$, contains the $[\text{Cu(H}_2\text{O})_6]^{2+}$ complex ion.
(i) A few drops of NH$_3$(aq) are added to CuSO$_4$(aq).
Describe any observations made.
[1]
(ii) Write an equation for the reaction taking place.
[1]
(c) (i) An excess of NH$_3$(aq) is added to CuSO$_4$(aq).
Describe any further observations made.
[1]
(ii)Write an equation for the reaction taking place.
[2]
(iii) State the name for the type of reaction taking place.(d) Copper metal can be oxidised by acidified KMnO$_4$. The relevant half-equations and their standard electrode potentials, $E^\circ$, are shown.
$$\text{Cu}^{2+} + 2\text{e}^- \rightleftharpoons \text{Cu}$$
$$\text{MnO}_4^- + 8\text{H}^+ + 5\text{e}^- \rightlefsharpoons \text{Mn}^{2+} + 4\text{H}_2\text{O}$$
$E^\circ = +0.34\text{V}$
(i) A MnO$_4^-$/Mn$^{2+}$ electrode is constructed using 0.0020 mol dm$^{-3}$ MnO$_4^-$, 1.0 mol dm$^{-3}$ MN$^{2+}$ and 1.0 mol dm$^{-2}$ H$^+$. The temperature used is 298K.
Use the Nernst equation to show that the $E$ value for this MnO$_4^-$/MN$^{2+}$ electrode is +1.49 V.
[2]
(ii) An electrochemical cell is constructed using a standard Cu$^{2+}/\text{Cu}$ electrode and the MnO$_4^-$/M n$^{2+}$ electrode described in (d)(i).
Calculate the value of 6 (a) Iron forms complex ions with the monodentate ligand, CN$^{-}$.
(i) Complex ion A contains one Fe$^{3+}$ ion and six CN$^{-}$ ligands.
Complex ion B contains one Fe$^{2+}$ ion and six CN$^{-}$ligands.
State the formulae of these two complex ions. Include the overall charge of each complex ion.
complex ion A ....
complex ion B ....
[1]
(ii) Explain why a solution containing complex ion A and a solution containing complex ion B are different colours.
....
....
....
[2]
(iii) In complex ion A, the carbon atom of each CN$^{-}$ ligand bonds to the Fe$^{3+}$ ion.
State the type of bonding involved.
....[1](b) Complex ions have different geometries. Complex ion A is octahedral. Ag⁺ ions form a linear complex with ammonia. Ni atoms form a tetrahedral complex with carbon monoxide molecules. The carbon atom in the monodentate carbon monoxide ligand bonds to the nickel atom. Pd²⁺ ions form a square planar complex with chloride ions. Complete Fig. 6.1 to show the geometry of each of these four ions, using three-dimensional bonds where necessary. Label one bond angle on each complex ion. Fig. 6.1 [4] [Total: 8]
7 A hydrocarbon is known to be either compound D or compound E. Fig. 7.1 (a) Give the systematic name of E. [1] (b) The proton (¹H) NMR spectra of D and E are compared. They are very similar. The proton (¹H) NMR spectrum of D is shown in Fig. 7.2. Fig. 7.2 (i) Suggest a suitable solvent for obtaining the spectrum in Fig. 7.2. [1] (ii) The proton (¹H)NMR spectrum of E is obtained twice, once before and once after shaking with D₂O. Describe any differences between these two spectra. Explain your answer. [1]
(iii) Complete Table 7.1 for the proton ($^1\text{H}$) NMR spectrum of D.
Table 7.1
| chemical shift $\delta$/ppm | number of $^1\text{H}$ atoms responsible for the peak | group responsible for the peak | splitting pattern |
| :--- | :---: | :---: | :---: |
| 1.3 | | | |
| 2.7 | | | |
| 7.1 | | |
Table 7.2
| environment of proton | example | chemical shift range $\delta$/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 |
| attached to alkene | =CHR | 4.5–6.0 |
| attached to aromatic ring | H–Ar | 6.0–9.0 |
| aldehyde | HCOR | 9.3–10.5 |
| alc(c) Compound D can be oxidised to compound F by alkaline KMnO₄ followed by dilute acid. Fig. 7.3 (i) Write an equation for this reaction using molecular formulae for D and F. The products of this reaction are F, water and carbon dioxide. Use [O] to represent one atom of oxygen from the oxidising agent. [1]
(ii) F reacts with an excess of SOCl$_2$ to form compound G. The molecular formula of G is C$_8$H$_4$Cl$_2$O$_2$.
G reacts with ethane-1,2-diol, HOCH$_2$CH$_2$OH, to form a mixture of products that includes compounds J, molecular formula C$_{10}$H$_8$O$_4$, and K, molecular formula C$_{18}$H$_{12}$Cl$_2$O$_6$.
Draw the structures of compounds G, J and K in Fig. 7.4.
Fig. 7.4
[3]
[Total: 11]8 Bromine reacts with methylbenzene in the dark in the presence of a suitable catalyst to form HBr and compound L, C$_7$H$_7$Br. L is one of three isomers that can form in this reaction.
(a) (i) The mechanism for the reaction involves methylbenzene reacting with a Br$^+$ ion. This ion is produced when bromine reacts with the catalyst.
Complete the equation for the reaction of Br$_2$ with the catalyst.
$$\text{Br}_2 + \rightarrow \text{Br}^+ + \text{ion}$$
[1]
(ii) One of the isomers of L forms in much smaller amounts than the other two isomers.
Draw the structure of this isomer and explain why it forms in the smallest amount.
[2]
(iii) Complete the mechanism in Fig. 8.1 for the reaction between methylbenzene and the Br$^+$ ion.
Include all relevant curly arrows and charges.
![Fig(b) Chlorobutane and chlorobenzene are added separately to samples of warm aqueous AgNO$_3$. One of the chloro-compounds reacts slowly and the other does not react. (i) Identify the chloro-compound that reacts and describe any observations. [1] (ii) Write two equations to explain any observations in (b)(i). [2] (iii) Explain the difference in reactivity of chlorobutane and chlorobenzene with warm aqueous AgNO$_3$. [2]
9 (a) Phenylamine, $C_6H_5NH_2$, and propylamine, $\text{CH}_3\text{CH}_2\text{CH}_2\text{NH}_2$, can be produced by different reduction reactions.
(i) Identify an organic compound that can be converted into $C_6H_5NH_$ by a reduction reaction. State the reagents and conditions for this reaction.
organic compound ...
reagents ...
conditions ... [2]
(ii) Identify an organic compound that can be convert into $\text{CH}_3\text{CH}_{2}\text{CH}_{2}\text{NH}_$ by a reduction reaction. State the reagent for this reaction.
organic compound ...
reactant ... [2]
(iii) Identify a single test that will distinguish between $C_6H_5NH_ $ and $\text{CH}_3\text{CH_{2}}\text{CH}_{2}\text{NH}_{2}$ by producing a white precipitate with only one of these amines.
Draw the structure of the compound tha(b) Describe the relative basicities of C$_6$H$_5$NH$_2$, CH$_3$CH$_2$CH$_2$NH$_2$ and NH$_3$. Explain your answer. least basic most basic [4] [Total: 10]
10 Propanoic acid, methanoic acid and ethanedioic acid are all weak acids. (a) Draw the displayed formula of ethanedioic acid. [1] (b) The three acids, propanoic acid, methanoic acid andethanedioic acid, can be distinguished using a combination of two chemical tests. Neither testing reagent is an acid–base indicator. Identify two suitable testing reagents and complete Table 10.1 to show the observations from each test. reagent 1 ... reagent 2 ..... Table 10.1 | | observation when treated with reagent 1 | observation when treated with reagent 2 | | :--- | :---: | :---: | | propanoic acid | | | | methanoic acid | | | | ethanedioic acid | | | (c) When propanoic acid is treated with chlorine gas in the presence of ultraviolet light, a mixture of products is formed. One of these produc