科目：化学 Chemistry (9701)
年份：2023 冬季
试卷：Paper 43
总页数：20
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, 29 Organic synthesis, 30 Analytical chemistry
1 Fluorine reacts with chlorine dioxide, $ClO_2$, as shown.
$$F_2(g) + 2ClO_2(g) \rightarrow 2FClO_2(g)$$
The rate of the reaction is first order with respect to the concentration of $F_2$ and first order with respect to the concentration of $ClO_2$. No catalyst is involved.
(a) (i) Suggest a two-step mechanism for this reaction.
step 1 $\rightarrow$
step 2 $\rightarrow$
[2]
(ii) Identify the rate-determining step in this mechanism. Explain your answer.
[1]
(b) When the rate of the reaction is measured in mol dm$^{-3}$ s$^{-1}$ the numerical value of the rate constant, $k$, is 1.22 under certain conditions.
(i) Complete the rate equation for this reaction, stating the overall order of the reaction.
rate =
overall order of reaction =
[1]
(ii) Use your rate equation in (i) to ca(c) Under different conditions, and in the presence of a large excess of ClO$_2$, the rate equation is as shown.
$$\text{rate} = k_1[\text{F}_2]$$
The half-life, $t_{\frac{1}{2}}$, of the concentration of F$_2$ is 4.00 s under these conditions.
(i) Calculate the numerical value of $k_1$, giving its units.
Give your answer to three significant figures.
$$k_1 = \dots\dots\dots\dots\quad\text{units}$$
(ii) An experiment is performed under these conditions in which the starting concentration of F$_2$ is 0.00200 mol dm$^{-3}$.
Draw a graph on the grid in Fig. 1.1 to show how the concentration of F$_2$ changes over the first 12 s of the reaction.
(iii) Use your graph in Fig. 1.1 to find the rate of the reaction when the concentration of F$_2$ is 0,00100 mol dm$^{-3}$.2 (a) Define $K_w$ mathematically by completing the expression.
$$K_w = \dots\dots\dots\dots\ldots\ldots\ldots\ldotp\ldots\ldots\ldots$$
(b) Two solutions, V and W, are described.
- V is HCl(aq).
- W is NaOH(aq).
- The concentration of HCl in V is the same as the concentration of NaOH in W.
- The pH values of V and W differ by exactly 11.00 at 298 K.
(i) Calculate the concentration of HCl in V.
concentration of HCl in V = $\dots\dots\dots\cdots\cdots\cdots\cdot\cdots\cdots\cdots$ mol dm$^{-3}$ [2]
(ii) Equal volumes of the two solutions V and W are mixed, giving solution X.
Name solution X and state its pH.
solution X ... pH ... [1]
(iii) A 1 cm$^3$ sample of 1.0 mol dm$^{-3}$ HNO$_3$ is added to 100 cm$^3$ of solution X, forming mixture Y.
A 1 cm$^3$ sample of1.0 mol dm$^{-3$ KO(ii) When concentrated $H_2SO_4$ is added to water a series of acid-base reactions occurs.
There are three conjugate acid-base pairs that can be identified during this series of reactions.
Write the formulae of these three conjugate acid-base pairs.
conjugate acid 1 ... conjugate base 1 ...
conjugate acid 2 ... conjugate base 2 ...
conjugate acid 3 ... conjugate base 3 ..... [2]
(d) The partition coefficient, $K_{pc}$, of a substance, $Q$, between hexane and water is 7.84 at 298 K.
$Q$ is more soluble in hexane than it is in water.
(i) Define partition coefficient, $K_{pc}$.
[1]
(ii) 5.00 g of $Q$ is shaken with a mixture of 100.0 cm³ of water and 100.0 cm³of hexane at 298 K and left until there is no further change in concentrations.
Calculate the mass of $Q$ dissolved in the wat3 Hydrogen peroxide is a liquid at 298 K. It is moderately stable under room conditions but will decompose quickly if a catalyst is added.
reaction 1 $2H_2O_2(I) \rightarrow 2H_2O (I) + O_2(g)$
(a) (i) Define entropy.
[1]
(ii) Predict the sign of the standard entropy change of reaction 1.
Explain your answer.
sign ...
explanation ...
[1]
(b) Some bond energy data are shown in Table 3.1.
Table 3.1
| type of bond | bond energy / kJ mol$^{-1}$ |
| :--- | :--- |
| O–O | 150 |
| O–H | 460 |
| O=O | 496 |
Use the data in Table 3.1 to show that the enthalpy change of the following reaction is $-196\text{kJ mol}^{-1}$.
$$2H_2O_2(g) \rightarrow 2H_2О(g) + O_2(g)$$(c) Some standard entropies, $S^\ominus$, are shown in Table 3.2.
Table 3.2
| substance | $S^\ominus$/JK$^{-1}$mol$^{-1}$ |
| :---: | :---: |
| $\text{H}_2\text{O}_2(\text{I})$ | +102 |
| $\text{H}_2\text{\text{O}}(\text{I})$ | +70 |
The enthalpy change and Gibbs free energy change for the following reaction are shown.
$$\text{2H}_2\text{O}_2(\mathrm{I}) \rightarrow \text{2H}_2\text{O}(\mathrm{I}) + \text{O}_2(\mathrm{g})$$
$$\Delta H^\ominus = -196 \text{kJ mol}^{-1}$$
$$\Delta G^\ominus = -238 \text{kJ mol}^{-1}$$
Use the data given to calculate the standard entropy of oxygen, $S^\ominus$, $\text{O}_2(\mathrm{g}).$
$$S^\ominus, \text{O}_2(\mathrm{ g })= \dots\dots\dots\dots\ldots\ldots\ldots\ldotting\ldots\ldots\ldots J K^{-1} \text{mol}^{-1}$$
(d) The decomposition of $\text{H}_2(e) The $E^\ominus$ values for two electrode reactions are given.
$$\text{H}_2\text{O}_2 + 2\text{H}^+ + 2\text{e}^- \rightleftharpoons 2\text{H}_2\text{O} \quad E^\ominus = +1.77\text{ V}$$
$$\text{Cr}^{3+} + \text{e}^- \rightlefthARc^{2+} \quad E^\ominus = -0.41\text{ V}$$
(i) An electrochemical cell is constructed with the following half-cells (electrodes):
• an acidified solution of $\text{H}_2\text{O}_�$, a platinum wire
• $\text{Cr}^{2+}$ mixed with $\text{Cr}^{3+}$, a platinum wire.
Identify the positive half-cell and calculate the standard cell potential, $E^\ominus_{\text{cell}}$.
positive half-cell ..... $E^\ominus_{\text{cell }} = \dots\dots\dots\dots\V$ [1]
(ii) Calculate the value of $\Delta G^\ominus$ for the cell reaction that occurs, per mole of $\text{H}_2\text{ O}_(g) (i) Define enthalpy change of hydration, $\Delta H_{\text{hyd}}$.
(ii) Aluminium fluoride, $AlF_3$, is an ionic solid.
Complete and label the energy cycle to show the relationship between:
- the enthalpy change of solution of $AlF_3$, $\Delta H^{\ominus}_{\text{sol}}
- the lattice energy of $AlF_3$, $\DeltaH^{\ominus}_{\text{latt}}
- the enthalpy changes of hydration of $Al^{3+}$ and $F^{-}$, $\DeltaH^{\ominus}_{\text {hyd}}$.
Include state symbols for all substances and ions.
(iii) Relevant data for this question are given.
$$\Delta H^{\ominus}_{\text{sol}} AlF_3 = -209 \text{ kJ mol}^{-1}$$
$$\Delta H^{\ominus}_{\mathrm{hyd}} Al^{3+} = -4690 \text{ kJ mol}^{-1}$$
$$\Delta H^{\ominus}_{\rm hyd} F^- = -506 \text{ kJ mol}^{-1}
Use these data and your energy cycle in (g)(ii) to c4 (a) Cobalt(II) nitrate, Co(NO$_3$)$_2$, is a reddish-brown crystalline solid. It dissolves in water to form a solution containing [Co(H$_2$O)$_6$]$^{2+}$ complex ions.
(i) Complete Table 4.1 giving the formula of the cobalt-containing species that is formed in each of the three reactions described.
Table 4.1
| reaction | reagent added to [Co(H$_2$O)$_六$]$^{2+}$ (aq) | cobalt-containing species formed |
| :--- | :---: | :---: |
| 1 | NaOH(aq) | |
| 2 | an excess of NH$_3$(aq) | |
| 3 | an excess of conc. HCl(aq) | |
(ii) Describe the colour change seen in reaction 3.
original colour of [Co(H$_2$O)$_六个$]$^{2+}(aq) ....
final colour after addition of an excess of conc. HCl(aq)
(b) Calcium nitrate, Ca(NO$_3$)$_二$, is a white crystalline solid. When heated, it starts to decompose at apprBLANK PAGE
5 Transition elements behave as catalysts and can form complex ions.
(a) Explain why transition elements behave as catalysts.
(b) Silver forms the linear complex ion $[\text{Ag}(\text{CN})_2]^{-}$.
Copper forms the tetrahedral complex ion $[\text{Cu}(\text{CN})_4]^{3-}$.
Titanium forms the complex $[\text{TiCl}_4(\text{diars})_2]$, where diars is a neutral bidentate ligand.
(i) State the oxidation state and the coordination number of titanium in $[\text{TiCl}_4(\mathrm{diars})_2]$.
oxidation state ...
coordination number ..... [1]
(ii) Draw three-dimensional diagrams to show the shapes of $[\text{Ag}(\text{CN })_2]^{-}$ and $[\text{Cu}(\text{CN })_4]^{3-}$, in the boxes.
Label one bond angle on each diagram.
(c) The numerical value of the stability constant, $K_{\text{stab}}$, of the (ii) In a solution the concentrations of CN$^{-}$ and [Cu(CN)$_4$$]^{3-}$ are both 0.0010 mol dm$^{-3}$.
Use your expression from (c)(i) and the value of $K_{\text{stab}}$ to calculate the concentration of Cu$^+$(aq) in this solution.
concentration of Cu$^+$(aq) = ..... mol dm$^{-3}$
(d) A piece of a copper-containing alloy has a mass of 0.567 g. It is dissolved in an acid giving 100.0 cm$^3$ of a blue solution in which all the copper is present as Cu$^{2+}$ ions.
An excess of KI(aq) is added to a 25.0 cm$^3$ sample of this solution.
All of the copper is precipitated as white CuI(s).
Cu$^{2+}$ ions are the only component in the solution that react with KI(aq). This is reaction 1.
reaction 1 $\quad 2\text{Cu}^{2+} + 4\text{I}^- \rightarrow 2\text{CuI} + I_2$
The liberated $I_2$ is t6 (a) Five ligands are listed in Table 6.1.
Table 6.1
| ligand | type of ligand |
| :--- | :--- |
| NH$_3$ | |
| EDTA$^{4-}$ | |
| CN$^{-}$ | |
| H$_2$NCH$_2$CH$_2$NHCH$_2$CH$_2$NH$_2$ | tridentate |
| C$_2$O$_4^{2-}$ | |
(i) Complete Table 6.1 using the words monodentate, bidentate and polydentate only.
Each of these three words may be used once, more than once, or not at all. [2]
(ii) The molecule H$_2$NCH$_2$Ch$_2$NHCH$_2$Ch$_2$NH$_2$ is a tridentate ligand.
Suggest the meaning of tridentate ligand.
[1]
(iii) Suggest how H$_2$NCH$_2$Cl$_2$NHCH$_2$Ch $_2$NH$_2$ acts as a tridentate ligand.
[1]
(b) Nickel forms the octahedral complex $[\text{Ni}(en)_2(\text{H}_2\text{O})_2]^{2+}$. This complex can exist in three isomeric forms, listed in Table 6.2.
One of these forms is a trans i7 Sunset Yellow is an additive used for colouring foods. A synthetic route for making Sunset Yellow is shown. Molecules E and G each contain one $-SO_3^-$ group. These groups are unchanged in the formation of Sunset Yellow.  (a) State the molecular formula of the Sunset Yellow anion. [1] (b) Deduce the structures of E, F and G and draw them in the boxes in Fig. 7.1. [3] (c) Suggest suitable reagents and conditions for step 1 and 2. step 1 ... step 2 ... [3] (d) Predict the number of peaks in the carbon-13 NMR spectrum of the Sunset Yellow anion. [Total: 8]
8 Capsaicin is found in chilli peppers. You should assume the CH$_3$O group is unreactive in the reactions involved in this question. (a) Name all the functional groups in capsaicin in addition to the CH$_3$O group. [1] (b) Complete the equation for the reaction of capsaicin with an excess of Br$_2$(aq) in the dark. Draw the structure of the organic product in the labelled box. (c) Capsaicin is heated with an excess of hydrogen gas in the presence of platinum metal. The six-membered ring reacts in the same way as benzene under these conditions. Draw the structure of the organic product formed. [2]
(d) When capsaicin is treated with reagent J under suitable conditions one of the products is methylpropanoic acid, CH$_3$CH(CH$_3$)COOH. (i) Identify reagent J and any necessary conditions. (ii) There are three different peaks in the proton (^1H) NMR spectrum of CH$_3$CH(CH$_3$(CH$_3$))COOH in CDC$l_3$. Table 8.1 | 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
(e) (i) Capsaicin is heated with an excess of hot aqueous NaOH.
Draw the structures of the two organic products H and K.
H $C_{8}H_{10}NO_2Na$
K $C_{10}H_{17}O_2Na$
(ii) Name the two types of reaction occurring in (e)(i).
[1]
(f) Draw the structure of the organic product L formed when capsaicin is treated with LiAlH$_4$ in dry ether.
[1]
[Total: 14]BLANK PAGE
9 (a) Benzoyl chloride, $C_6H_5COCl$, can be made from ethyl benzene in a two-step process. A reaction scheme is shown. (ii) Draw the intermediate organic compound $M$ in the box. [1] (iii) Identify the type of reaction in step 1 and step 2. step 1 ... step 2 ... [2]
(b) $C_6H_5COCl$ reacts with phenol, $C_6H_5OH$, to give the ester phenyl benzoate, $C_6H_5COOC_6H_5$. An incomplete description of the mechanism of this reaction is shown in Fig. 9.1.  (i) Complete the mechanism in Fig. 9.1 and include: - all relevant dipoles ($\delta+$ and $\delta-$) and full electric charges (+ and –) on the species in box one and in box two - all relevant lone pairs on the species in box one and in boxtwo - all relevant curly arrows to show the movement of electron pairs in box one and in box two - the formula of the second product in box three. [4] (ii) Name this mechanism. [1] (c) Benzoyl chloride, chlorobenzene and chloroethane differ in their rates of hydrolysis when each compound is added separately to water at 25°C. Suggest the relative