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(a) Complete the table with information for two of the particles in an atom of ^{197}Au.
[Table_1]
particle relative mass relative charge location within atom total number in an atom of ^{197}Au
electron 0.0005 -1 79
neutron nucleus
[4]
(b) State the type of bonding in gold.
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[1]
(c) A sample of gold found in the earth consists of only one isotope.
(i) Explain what is meant by the term isotopes.
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[2]
(ii) A different sample of gold contains more than one isotope.
Suggest why this different sample of gold has the same chemical properties as the sample found in the earth.
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[1]
(d) Tumbaga is an alloy of copper and gold. A sample of tumbaga was analysed. The mass spectrum of the sample is shown.
(i) Calculate the percentage abundance of gold, x, in the sample of tumbaga.
x = .................................... % [1]
(ii) Calculate the relative atomic mass, A_r, of the copper present in this sample. Give your answer to two decimal places.
A_r (Cu) = .................................... [2]
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Complete the table to show the bonding in the elements, and the formulae of their oxides and chlorides.
[3]
(b) $\text{SCl}_2$ is formed in the following reaction.
$$\text{S}_2\text{Cl}_2(l) + \text{Cl}_2(g) \rightleftharpoons 2\text{SCl}_2(l) \quad \Delta H = -40.6 \text{kJ mol}^{-1}$$
(i) Complete the 'dot-and-cross' diagram to show the bonding in a molecule of $\text{SCl}_2$. Show outer electrons only.
[1]
(ii) Complete and fully label the reaction pathway diagram for the reaction between $\text{S}_2\text{Cl}_2$ and $\text{Cl}_2$. Include labels for activation energy, $E_a$, and enthalpy change of the forward reaction, $\Delta H$.
[2]
(c) (i) On the axes, sketch the trend in melting point of the elements $\text{Na to S}$.
[1] (ii) Give three statements to explain your sketch.
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3 .................................................................................................................................................................. .................................................
[3]
(d) Write an equation for the reaction of $\text{P}_4\text{O}_{10}$ with water.
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[1]
(e) $\text{SO}_2$ can be released into the atmosphere when fossil fuels containing sulfur are burnt.
State and explain one environmental consequence of the release of $\text{SO}_2$ into the atmosphere.
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[2]
(f) The elements in the third period show a general increase in their first ionisation energies from left to right.
Identify two pairs of successive elements in the third period that do not agree with this statement. For each pair, explain why the change in ionisation energy does not agree with this statement.
Use of the Data Booklet may help you to answer this question.
pair 1 ......................................................................................................
explanation ............................................................ ................................................. .................................................................................................................................. .................................................
pair 2 ......................................................................................................
explanation ............................................................ ................................................. .................................................................................................................................. .................................................
[4]
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Trihalomethanes are organic molecules in which three of the hydrogen atoms of methane are replaced by halogen atoms, for example CHF₃.
(a) The equation shows a reaction to produce CHF₃.
$$\text{CHI}_3(s) + 3\text{AgF}(s) \rightarrow \text{CHF}_3(g) + 3\text{AgI}(s)$$
Use the data to calculate the enthalpy change of reaction, ΔH₁, for this formation of CHF₃.
[Table_1]
enthalpy change of reaction, ΔH₁ = ............................ kJ mol⁻¹ [3]
(b) The graph shows the relationship between $pV$ and $p$ at a given temperature for CHF₃ and an ideal gas.
(i) CHF₃ is not an ideal gas.
State three basic assumptions that scientists make about the properties of ideal gases.
1 ...............................................................................................................................
2 ...............................................................................................................................
3 ............................................................................................................................... [3]
(ii) Explain why CHF₃ deviates from the properties of an ideal gas at pressures greater than 300 atm.
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[2]
(c) A different trihalomethane, CHCl₃, reacts with O₂ to produce carbonyl dichloride. HCl(g) is also released as a product of this reaction.
(i) Write an equation for this reaction of CHCl₃ with O₂.
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(ii) The conversion of CHCl₃ to carbonyl dichloride can be monitored by infra-red spectroscopy. The infra-red spectrum of carbonyl dichloride is shown.
On the infra-red spectrum of carbonyl dichloride identify with an X the absorption that would not be present in an infra-red spectrum of CHCl₃. Explain your answer.
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[2]
(iii) Suggest another difference between the infra-red spectra of CHCl₃ and carbonyl dichloride.
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[1]
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The diagram shows a reaction sequence starting from ethanal.
(a) (i) Draw the displayed formula of P. [1]
(ii) Name the type of chemical reaction that occurs in reaction 3. [1]
(iii) Write an equation to represent reaction 4. Use [O] to represent the oxidising agent. [1]
(iv) State the reagents and conditions for reaction 4. [1]
(b) Compound Q is formed as a mixture of two optical isomers.
(i) Explain what is meant by the term optical isomers. [1]
(ii) Draw the two optical isomers of Q, showing clearly their three-dimensional structures. [2]
(c) R can be used to make a polymer, W, in two steps.
Draw one repeat unit of W. [3]
(d) Compound Z, $H_2C=CHCH_3$, is produced from R. Z can be used in a two-step process to produce 2-aminopropane.
(i) In the first step, Z reacts with HBr to form two products. The structure of the product depends on which intermediate is formed, intermediate I or intermediate II. Explain why intermediate I is more likely to form than intermediate II. [2]
(ii) When intermediate I forms, the product of the first step is T. Complete the diagram to show the mechanism for the conversion of Z to T. Include all relevant charges, partial charges, curly arrows and lone pairs. [3]
(iii) T can then be converted to 2-aminopropane. Name the mechanism for this conversion. [1]
(e) (i) Compound S, $CH_3COCO_2H$, can be reduced by $LiAlH_4$. Complete the equation using structural formulae to represent this reaction. Use [H] to represent the reducing agent. [2]
Other reducing agents containing Group 1 metal cations include $LiBH_4$, $NaBH_4$ and $KBH_4$. The strength of the reducing agent depends on the size of its cation.
(ii) Give the electronic configuration of the $Na^+$ cation. [1]
(iii) Suggest why ionic radius increases down Group 1. [1]
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