科目：化学 Chemistry (9701)
年份：2019 春季
试卷：Paper 42
总页数：19
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) State one natural and one man-made occurrence of oxides of nitrogen.
[1]
(b) Under conditions of high pressure and a catalyst, nitrogen monoxide, NO, forms two other oxides of nitrogen, dinitrogen monoxide, $N_2O$, and dinitrogen trioxide, $N_2O_3$.
$$NO(g) \rightarrow N_2O(g) + N_2O_3(g) \quad \Delta H^\circ = -195.2\text{ kJ mol}^{-1} \\
\Delta G^\circ = -102.8\text{ kJ mol}^{-1}$$
(i) Balance the equation above for the formation of $N_2O$ and $N_2O_3$ from NO. [1]
(ii) State how the oxidation number of nitrogen changes during this reaction.
$$\text{NO} \rightarrow N_2O \quad \text{from } ... \rightarrow ...$$
$$\text{NO} \rightarrow \text{N}_2\text{O}_3 \quad \text{from } ... \Rightarrow ...$$
(iii) Calculate the e(c) At room temperature $N_2O_3$ dissociates.
$$N_2O_3(g) \rightleftharpoons NO(g) + NO_2(g)$$
(i) Write the expression for $K_p$ for this equilibrium. Include the units in your answer.
$$K_p =$$
units = ..... [1]
A 1.00 dm³ flask at 25°C is filled with pure $N_2O_3(g)$ at an initial pressure of 0.60 atm.
At equilibrium, the partial pressure of $NO_2(g)$ is 0.48 atm.
(ii) Calculate the partial pressures of NO(g) and $N_2O_3(g)$at equilibrium. Hence calculate the value of $K_p$ at 25°C.
$$p(\text{NO}(g)) =$$
$$p(N_2O_3(g)) =$$
$$K_p =$$(d) NO reacts readily with oxygen.
$$2\text{NO}(g) + \text{O}_2(g) \rightarrow 2\text{NO}_2(g)$$
The table shows how the initial rate of this reaction at $25^{\circ}\text{C}$ depends on the initial concentrations of the reactants.
| initial concentration / mol dm$^{-3}$ | initial rate / mol dm$^{-3}$ s$^{-1}$ |
| :--- | :--- |
| [NO(g)] | [O$_2$(g)] |
| 0.100 | 0.0500 | 3.50 |
| 0.0500 | 0.100 | 1.75 |
| 0.0500| 0.0500|0.875 |
(i) Deduce the order of reaction with respect to each reactant. Explain your reasoning.
order with respect to [NO(g)]
order with respect to [O$_2$(g)]
[2]
(ii) State the rate equation for this reaction. Use the rate equation to calculate the rate constant. Include the units for the rate constant in your answer.
rate =
rate constant, $k =$ .....
units of $k(e) NO reacts with iron pentacarbonyl, Fe(CO)$_5$, as shown. NO and CO are both monodentate ligands.
$$\text{Fe(CO)}_5 + 2\text{NO} \rightarrow \text{Fe(CO)}_2(\text{NO})_2 + 3\text{CO}$$
During this reaction the co-ordination number of the iron changes.
(i) State what is meant by the term co-ordination number.
[1]
(ii) Describe how the co-ordination number of the iron Changes during this reaction.
from ... to ..... [1]
(iii) Only one stereoisomer of Fe(CO)$_2$(NO)$_2$ exists.
Use this information to suggest the geometry of the complex.
[1]
(f) The complex Ru(NO)L$_2$Cl$_3$ exists in three isomeric forms. L represents the monodentate ligand C$_6$H$_5$P(CH$_3$)$_2$.
(i) Complete the three-dimensional diagrams to show the three isomers of Ru(NO)L$_2$Cl $_3$.
[2]
(ii) Suggest the t2 (a) The following table lists the solubilities of the hydroxides and carbonates of some of the Group 2 elements, M, at $25^{\circ}\mathrm{C}$.
| element M | solubility/mol dm$^{-3}$ |
| :--- | :--- |
| $\text{M(OH)}_2$ | $1.5 \times 10^{-3}$ |
| $\text{MCO}_3$ | $1.3 \times 10^{-4}$ |
(i) Explain why the solubility of the Group 2 hydroxides, $\text{M(OH)}_2$, increases down the group.
[3]
(ii) Suggest a reason for the general decrease in the solubility of the Group 2 carbonates, $\text{MCO}_3$, down the group.
[1]
(iii) When carbon dioxide is passed through a saturated solution of calcium hydroxide (limewater), a white precipitate of calcium carbonate is formed.
Use the data in the table to deduce, for each of Mg, Sr and Ba, whether or not a saturated solution of its hydroxide cou(b) (i) Calculate the value of the solubility product, $K_{sp}$, of magnesium hydroxide at 25 °C.
$$K_{sp} = \dots\dots\dots\dots\ldots\ldots\ldots\ldotp$$
(ii) State what would be observed if a few drops of a saturated solution of barium hydroxide are added to a saturated solution of barium carbonate. Explain your answer.
observation .....
explanation .....
[2]
(c) The equation for the formation of the gaseous hydroxide ion is shown.
$$\frac{1}{2}H_2(g) + \frac{1}{2}O_2(g) + e^- \rightarrow OH^-(g) \quad \Delta H = \Delta H_f^\circ(OH^-(g))$$
Use data in the table and from the Data Booklet to calculate $\Delta H_f^\circ(OH^−(g))$. You might find it useful to construct a Born-Haber cycle.
| enthalpy change | $\Delta H^\circ$/kJ mol$^{-1}$ |
| :--- | :---: |
| atomisation of Mg(s3 (a) (i) Use mathematical expressions to define the following terms.
• pH = ..... [2]
• $K_a$ for a weak acid, HA = ..... [2]
(ii) Write equations to show how a buffer solution consisting of a mixture of HA(aq) and NaA(aq) controls pH when an acid or an alkali is added.
[2]
(b) When chlorine dissolves in water the following reaction occurs.
$$Cl_2(g) + H_2O(l) \rightarrow HClO(aq) + H^+(aq) + Cl^-(aq)$$
When solutions of chlorine are used for water purification, the pH of the solution of chlorine is kept near to pH 7 by the addition of a base.
Chlorine is dissolved in water to produce $1000\text{ cm}^3$ of a solution containing $0.170\text{ mol}$ of HClO and $0.170\text{ mol}$$\text{ of HCl}$.
A buffer solution is then prepared by adding $0.200\text{ mol}$ of NaOH(s) to this solu4 (a) (i) Complete the electronic configuration of a copper atom.
$$1s^2 2s^2 2p^6$$
(ii) • Explain why most copper(II) salts are coloured.
• Suggest why copper(I) salts are usually white.
(b) Brass is an alloy of copper and zinc. The following reaction can be used to determine the amount of copper in a sample of brass.
$$2Cu^{2+}(aq) + 4I^{-}(aq) \rightarrow 2CuI(s) + I_2(aq)$$
The procedure was carried out using the following steps.
• A solution of $Cu^{2+}(aq)$ was obtained by dissolving a 1.50 g sample of brass in concentrated sulfuric acid and diluting with water.
• An excess of $I^{-}(aq)$ was added.
• The iodine produced was titrated against a 0.500 mol dm$^{-3}$ solution of thiosulfate ions, $S_2O_3^{2-}(aq)$.
$$I_2(aq) + 2S_2O_3^{2-}(\text{aq}) \rightarrow 2I^{-}(aq) + S_4(c) (i) Use standard electrode potential data from the Data Booklet to calculate $E_{\text{cell}}^{\circ}$ for the reaction.
$$2\text{Cu}^{2+}(\text{aq}) + 4\text{I}^-(\text{aq}) \rightarrow 2\text{CuI(s)} + \text{I}_2(\text{aq})$$
$E_{\text{cell}}^{\circ} = \dots\dots\dots\dots\mathrm{V}$ [1]
(ii) Explain how the value of $E_{\text{cell}}^{\circec}$ calculated in (i) predicts that the reaction is not likely to occur.
[1]
In an experiment, a solution of $\text{I}^-(\text{aq})$ is added to a solution of $\text{Cu}^{2+}(\text{aq}).$ A reaction does occur and a precipitate of sparingly soluble CuI(s) is formed.
The concentration of $\text{Cu}^{2+}(\mathrm{aq})$ remaining in the solution is $1.00 \text{mol dm}^{-3}$.
The concentration of $\text{Cu}^{+}(\mathrm{aq})$ in a saturated soluti(d) When chloride ions are added to a solution containing Cu$^{2+}$(aq), the complex ion [CuCl$_4$]$^{2-}$(aq) is formed.
(i) State the colours of Cu$^{2+}$(aq) and [CuCl$_4$]$^{2−}$(aq).
$$\text{Cu}^{2+}(\text{aq}) \quad \cdots$$
$$[\text{CuCl}_4]^{2-}(\text{aq}) \quad \cdot$$
[1]
(ii) Name the type of reaction that occurs when [CuCl$_4$]$^{2$-}(aq)$ is formed from Cu$^{2+}$(aq).
... [1]
(iii) Write an expression for the stability constant, $K_{\text{stab}}$, for [CuCl$_4$]$^{2-$}(aq)$. Include the units in your answer.
$$K_{\text{stab}} =$$
units = ... [2]
[Total: 17]5 (a) Methyl 2-cyanoprop-2-enoate, W, is the major component of Super Glue, a rapid-setting adhesive. As the adhesive sets, the monomer W polymerises. (i) Draw a section of the polymer showing two repeat units. (ii) Name the type of polymerisation occurring. (iii) Suggest two types of intermolecular force that could occur between the Super Glue polymer and the objects glued together. For each type of intermolecular force, refer to the atoms/groups in the Super Glue polymer involved in the attraction. | type of intermolecular force | atoms/groups in the Super Glue polymer | | :--- | :--- | | | |
(b) W can be synthesised in three steps, starting from 2-oxopropanoic acid, X. (i) Suggest the identities of compounds Y and Z by drawing their structures in the boxes. [2] (ii) Suggest suitable reagents and conditions for each of the steps 1–3. step 1 ..... step 2 ..... step 3 ..... [4] [Total: 11]
6 The names of many drugs used in medicine often include parts of the names of the functional groups their molecules contain.
(a) Suggest two functional groups present in a molecule of the drug named chloramphenicol.
1 ....
2 ....
(b) The drug named ketamine readily reacts with protons as shown.
$$\text{ketamine} + \text{H}^+ \rightarrow [\text{ketamine-H}]^+$$
(i) State the role of ketamine in this reaction.
[1]
Ketamine gives an orange precipitate with 2,4-dinitrophenylhydrazine (2,4-DNPH).
(ii) Suggest the functional group in the ketamine molecule responsible for this observation.
[1]
The mass spectrum of ketamine is determined. Two peaks close to the molecular ion peak, M, are observed with the relative abundances shown in the table.
| peak | m/e | relative abundance |
| :--- | (v) Another peak in the mass spectrum of ketamine has an m/e value of 240.
Predict the relative abundance of this peak.
relative abundance = ..... [1]
(vi) Use the information in (b) to complete the molecular formula of ketamine by working out the identities of the three different heteroatoms and the number of hydrogen atoms present.
$$\text{C}_{13}\text{H}$$
[1](c) Neramexane is another drug. (i) Suggest the number of peaks in the carbon-13 NMR spectrum of neramexane. [1] The proton (¹H) NMR spectrum of neramexane in CDCl₃ shows five peaks with the following chemical shifts ($\delta$). | $\delta$/ppm | number of protons responsible | splitting pattern (singlet, doublet, triplet, quartet or multiplet) | | :--- | :---: | :---: | | 0.9 | | singlet | | 1.2 | 3 | | | 1.4 | 2 | | | 1.7 | 4 | | | 2.2 | | broad singlet | (ii) Complete the table. [4]
(iii) Use the Data Booklet and the table in (c)(ii) to complete the assignment of the correct $\delta$ values to each of the circled hydrogen atoms on the structure of neramexane.
[2]
(iv) One of the peaks in the proton ($^1\text{H}$) NMR spectrum disappears when the sample is shaken with $D_2\text{O}$.
Identify the peak and explain why it disappears.
[Total: 15]7 Ethanedioyl dichloride, ClCOCOCl, is a useful reagent in organic synthesis. It can be made from compound A in one step.
(a) (i) Suggest the identity of compound A by drawing its structure in the box. [1]
(ii) State the reagents and conditions needed to convert A into ClCOCOCl.
Ethanedioyl dichloride is used in the following synthesis of compound Q. It is used in a 1:1 stoichiometric ratio with B in step 2.
step 1
B (C$_6$H$_5$Cl)
ClCOCOCl + AlCl$_3$
C (C$_8$H$_4$O$_2$Cl$_2$)
step 2
D
step 4
NH$_2$
step 5
E (C$_{14}$H$_{10}$NO$_2$Cl)
step 6
Q(b) (i) Suggest the identities of the compounds B–E by drawing their structures in the boxes. [4]
(ii) State the reagents and conditions for the following steps.
step 1 ...
step 3 ...
step 4 ...
step 6 ... [5]
If the amount of ClCOOCI used in step 2 is decreased, another compound is formed in step 2 with the molecular formula C$_{14}$H$_{8}$O$_2$Cl$_2$.
(iii) Suggest the structure of this compound.
$$\text{C}_{14}\text{H}_8\text{O}_2\text{Cl}_2$$
[1]
(iv) Identify all the steps in the synthesis of Q from benzene that are electrophilic substitution reactions.
... [1]
Question 7 continues on page 20.(c) Draw structures of the compounds formed when Q is treated with the following reagents. If there is no reaction, write ‘no reaction’ in the box.
$$\text{heat with } \text{Cr}_2\text{O}_7^{2-} / \text{H}^+(\text{aq})$$
$$\text{heat with NaOH}(\text{aq})$$
$$\text{Rb}_2(\text{aq})$$
$$\mathrm{HCl}(\text{aq})$$
room temperature
[Total: 17]