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For each of the following, name an element which matches the description.
(a) It is used as a fuel in nuclear reactors.
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(b) It is the only non-metal which is a good conductor of electricity.
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(c) Inert electrodes are made from this metal.
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(d) This gaseous element is used to fill balloons in preference to hydrogen.
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(e) An element which can form an ion of the type $X^{3-}$.
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(f) It has the same electron distribution as the calcium ion, $\text{Ca}^{2+}$.
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(g) The element is in Period 5 and Group VI.
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545
500
577
(a) Give three differences in physical properties between the Group I metal, potassium, and the transition element, iron.
1. .....................................................
2. .....................................................
3. ..................................................... [3]
(b) The following metals are in order of reactivity.
potassium
zinc
copper
For those metals which react with water or steam, name the products of the reaction,
otherwise write ‘no reaction’.
potassium .....................................................
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zinc .........................................................
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copper .......................................................
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521
523
584
Ammonia is manufactured by the Haber process.
$$\text{N}_2(g) + 3\text{H}_2(g) \rightleftharpoons 2\text{NH}_3(g)$$
The forward reaction is exothermic.
(a) Describe how the reactants are obtained.
(i) Nitrogen
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(ii) Hydrogen
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(b) The percentage of ammonia in the equilibrium mixture varies with temperature and pressure.
(i) Which pair of graphs, A, B or C, shows correctly how the percentage of ammonia at equilibrium varies with temperature and pressure?
!(data:image/png;base64,...)
The pair with both graphs correct is .................................................................. [1]
(ii) Give a full explanation of why the pair of graphs you have chosen in (i) is correct.
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(iii) Catalysts do not alter the position of equilibrium. Explain why a catalyst is used in this process.
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575
533
543
20.0 g of small lumps of calcium carbonate and 40 cm$^3$ of hydrochloric acid, concentration 2.0 mol/dm$^3$, were placed in a flask on a top pan balance. The mass of the flask and contents was recorded every minute.
The mass of carbon dioxide given off was plotted against time.
$\text{CaCO}_3(s) + 2\text{HCl}(aq) \rightarrow \text{CaCl}_2(aq) + \text{H}_2\text{O}(l) + \text{CO}_2(g)$
In all the experiments mentioned in this question, the calcium carbonate was in excess.
(a) (i) Explain how you could determine the mass of carbon dioxide given off in the first five minutes.
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(ii) Label the graph F where the reaction rate is the fastest, S where it is slowing down and 0 where the rate is zero. [2]
(iii) Explain how the shape of the graph shows where the rate is fastest, where it is slowing down and where the rate is zero.
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(b) Sketch on the same graph, the line which would have been obtained if 20.0 g of small lumps of calcium carbonate and 80 cm$^3$ of hydrochloric acid, concentration 1.0 mol/dm$^3$, had been used. [2]
(c) Explain in terms of collisions between reacting particles each of the following.
(i) The reaction rate would be slower if 20.0 g of larger lumps of calcium carbonate and 40 cm$^3$ of hydrochloric acid, concentration 2.0 mol/dm$^3$, were used.
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(ii) The reaction rate would be faster if the experiment was carried out at a higher temperature.
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(d) Calculate the maximum mass of carbon dioxide given off when 20.0 g of small lumps of calcium carbonate react with 40 cm$^3$ of hydrochloric acid, concentration 2.0 mol/dm$^3$.
$\text{CaCO}_3(s) + 2\text{HCl}(aq) \rightarrow \text{CaCl}_2(aq) + \text{H}_2\text{O}(l) + \text{CO}_2(g)$
number of moles of HCl used =
mass of carbon dioxide = ............... g [4]
550
559
532
(a) The following hydrocarbons are isomers.
CH$_3$—CH—CH═CH$_2$
‖
CH$_3$
CH$_3$—CH$_2$—CH$_2$—CH═CH$_2$
(i) Explain why these two hydrocarbons are isomers.
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(ii) Give the structural formula of another hydrocarbon which is isomeric with the above. [1]
(b) Give the structural formula and name of each of the products of the following addition reactions.
(i) ethene and bromine
structural formula of product
name of product .................................................................................... [2]
(ii) propene and hydrogen
structural formula of product
name of product .................................................................................... [2]
(iii) but-1-ene and water
structural formula of product
name of product .................................................................................... [2]
(c) Alkenes can be oxidised to carboxylic acids.
(i) For example, propene, CH$_3$—CH═CH$_2$, would produce ethanoic acid, CH$_3$—COOH, and methanoic acid, H—COOH. Deduce the formulae of the alkenes which would form the following carboxylic acids when oxidised.
ethanoic acid and propanoic acid
only ethanoic acid [2]
(ii) Describe the colour change you would observe when an alkene is oxidised with acidified potassium manganate (VII).
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(d) Alkenes polymerise to form addition polymers.
Draw the structural formula of poly(cyanoethene), include at least two monomer units. The structural formula of the monomer, cyanoethene, is given below.
C═C
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H CN [3]
594
551
589
(a) Lead has a typical metallic structure which is a lattice of lead ions surrounded by a 'sea' of mobile electrons. This structure is held together by attractive forces called a metallic bond.
(i) Explain why there are attractive forces in a metallic structure.
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(ii) Explain why a metal, such as lead, is malleable.
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(b) Basic lead(II) carbonate is heated in the apparatus shown below. Water and carbon dioxide are produced.
(i) Silica gel absorbs water. Silica gel often contains anhydrous cobalt(II) chloride. When this absorbs water it changes from blue to pink. Suggest a reason.
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(ii) Soda lime is a mixture of sodium hydroxide and calcium oxide. Why do these two substances react with carbon dioxide?
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(iii) Name two substances formed when soda lime reacts with carbon dioxide.
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(c) Basic lead(II) carbonate has a formula of the type $x\text{PbCO}_3.y\text{Pb(OH)}_2$ where $x$ and $y$ are whole numbers. Determine $x$ and $y$ from the following information.
$$\text{PbCO}_3 \rightarrow \text{PbO} + \text{CO}_2$$
$$\text{Pb(OH)}_2 \rightarrow \text{PbO} + \text{H}_2\text{O}$$
When heated, the basic lead(II) carbonate gave $2.112 \text{ g}$ of carbon dioxide and $0.432 \text{ g}$ of water.
Mass of one mole of $\text{CO}_2 = 44 \text{ g}$
Mass of one mole of $\text{H}_2\text{O} = 18 \text{ g}$
Number of moles of $\text{CO}_2$ formed = ..................... [1]
Number of moles of $\text{H}_2\text{O}$ formed = ..................... [1]
$x = ..................... \text{ and } y = .....................$
Formula of basic lead(II) carbonate is .......................................................... [1]
527
508
514
(a) The following are two examples of substitution reactions. Only the reaction involving chlorine is a photochemical reaction.
$$\text{CH}_4 + \text{Cl}_2 \rightarrow \text{CH}_3\text{Cl} + \text{HCl}$$
$$\text{CH}_4 + \text{Br}_2 \rightarrow \text{CH}_3\text{Br} + \text{HBr}$$
(i) Explain the phrase substitution reaction.
\text{...............................................................................................................................}
\text{...............................................................................................................................} [1]
(ii) How do photochemical reactions differ from other reactions?
\text{...............................................................................................................................}
\text{...............................................................................................................................} [1]
(b) Bond forming is exothermic, bond breaking is endothermic. Explain the difference between an exothermic reaction and an endothermic reaction.
\text{...............................................................................................................................}
\text{...............................................................................................................................} [2]
(c) Use the bond energies to show that the following reaction is exothermic. Bond energy is the amount of energy (kJ/mol) which must be supplied to break one mole of the bond.
Bond energies in kJ/mol
$$\text{Cl-Cl} +242$$
$$\text{C-Cl} +338$$
$$\text{C-H} +412$$
$$\text{H-Cl} +431$$
bonds broken \hspace{1cm} energy in kJ/mol
\text{......................} \hspace{2cm} \text{..............................}
\text{......................} \hspace{2cm} \text{..............................}
total energy = \text{..............................}
bonds formed \hspace{1cm} energy in kJ/mol
\text{......................} \hspace{2cm} \text{..............................}
\text{......................} \hspace{2cm} \text{..............................}
total energy = \text{..............................}
\text{...............................................................................................................................}
\text{...............................................................................................................................} [4]
593
576
520
