1.	Hydrogen forms compounds with most non-metallic elements and with some metals.
(a)	Calculate the empirical formula of the compound used in the manufacture of artificial rubber which has the following composition by mass.
	Hydrogen 11.1%	Carbon 88.9%

(3)
 
(b)	The boiling temperatures of hydrogen chloride and hydrogen iodide are:
	Hydrogen chloride	–85ºC
	Hydrogen iodide 	–35ºC
	Explain why hydrogen iodide has a higher boiling temperature than hydrogen chloride.
................................................................................................................................
................................................................................................................................
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(2)
 
(c)	Draw and explain the shapes of:
(i)	the PH3 molecule;

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(2)

(ii)	the AlH4– ion.

......................................................................................................................
......................................................................................................................
(2)
 
(d)	Calculate the number of molecules in 8.0 cm3 of gaseous phosphine, PH3, at room temperature and pressure.
	(The molar volume of a gas at room temperature and pressure should be taken as 2.4 × 104 cm3 mol–1.  The Avogadro constant is 6.0 × 1023 mol–1.)

(2)
(Total 11 marks)

2.	In the Periodic Table, where elements are arranged by atomic number, chlorine is a p-block element whereas manganese, a transition element, is in the d-block.
(a)	(i)	Define the term atomic number.
......................................................................................................................
......................................................................................................................
(1)

(ii)	Define the term d-block element
......................................................................................................................
......................................................................................................................
(1)
 
(iii)	Define the term transition element.
......................................................................................................................
......................................................................................................................
......................................................................................................................
(1)
 
(b)	The electron configuration of chlorine is 1s2 2s2 2p6 3s2 3p5. Write the electron configuration for manganese in a similar manner.
................................................................................................................................
(1)
 
(c)	(i)	Define the terrm first ionisation energy of chlorine.
......................................................................................................................
......................................................................................................................
......................................................................................................................
(2)

(ii)	Sketch the pattern you would expect to see in a plot of successive ionisation energies of chlorine against the number of electrons removed.

(3)
 
(d)	Manganese(IV) oxide, MnO2, reacts with concentrated hydrochloric acid to produce chlorine, water and a salt.  The salt has a composition of 43.7% manganese and 56.3% chlorine by mass.
Determine the empirical formula of the salt.

(3)
(Total 12 marks)

3.	(a)	Sodium reacts with cold water.
(i)	What would you see as the reaction proceeds?
..........................................................................................................................
..........................................................................................................................
..........................................................................................................................
(2)
 
(ii)	Write the balanced chemical equation for this reaction.
..........................................................................................................................
(2)
 
(b)	Calculate the volume of gas produced if 3.0 g of sodium reacts with an excess of water.
	(One mole of any gas at the temperature and pressure of the experiment occupies
24 dm3.)

(3)
(Total 7 marks)

4.	(a)	A compound of sodium, chlorine and oxygen contains, by mass, 21.6% Na, 33.3% Cl and 45.1% O. Show that this is consistent with the formula NaClO3.

(2)
 
(b)	NaClO3 can be obtained from NaOCl(aq) by a disproportionation reaction on heating.
(i)	Give the ionic equation for this disproportionation reaction.
..........................................................................................................................
(2)
 
(ii)	By a consideration of the oxidation numbers of the chlorine in the various species, show why the reaction in (i) is disproportionation.
..........................................................................................................................
..........................................................................................................................
..........................................................................................................................
..........................................................................................................................
..........................................................................................................................
(4)
 
(c)	Chlorine is used in the extraction of bromine from seawater.
(i)	Give the half-equation for the reduction of chlorine.
..........................................................................................................................
 
(1)
(ii)	Give the half-equation for the oxidation that is occurring given that the overall equation for the reaction is:
Cl2(aq) + 2Br–(aq) ® Br2(aq) + 2Cl–(aq)
..........................................................................................................................
..........................................................................................................................
(1)
(Total 10 marks)

5.	(a)	In an experiment to standardise an aqueous solution of sodium hydroxide 0.25 g of solid sulphamic acid, NH2SO3H, was dissolved in distilled water in a conical flask. When the aqueous sodium hydroxide was run into the flask from a burette 23.45 cm3 was required to exactly react with the sulphamic acid solution. The equation for the reaction is:
NH2SO3H(aq) + NaOH(aq) ® NH2SO3Na(aq) + H2O(l)
 
(i)	Calculate the amount (number of moles) of sulphamic acid in 0.25 g.
Mr(NH2SO3H) = 97.0.

(1)
 
(ii)	State the amount (number of moles) of sodium hydroxide in 23.45 cm3 of solution and hence calculate the concentration of the solution in mol dm–3.

(3)
 
(b)	The balance used to weigh the sulphamic acid is accurate to ±0.01 g. Calculate the percentage error in the mass of the sulphamic acid weighed.

(1)

(c)	An alternative method to that described in (a) involves making an aqueous solution of sulphamic acid of accurately known concentration.
	Describe a procedure bv which you would prepare 250 cm3 of aqueous sulphamic acid of accurately known concentration. Assume that you are provided with a weighing bottle containing between 2.40 g and 2.50 g of sulphamic acid and that this is a suitable mass to use.
In your answer give full practical details including the name of each piece of apparatus used, how each would be prepared for the procedure and how you would calculate the concentration (in mol dm–3) of the sulphamic acid solution. State, with a reason, one appropriate safety precaution that should be taken.
....................................................................................................................................
....................................................................................................................................
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(Allow one lined page)
(8)
(Total 13 marks)

6.	(a)	Complete and balance the following equations:
(i)	Ca + O2 ® .....................................................................................................
(1)
(ii)	Na2O + H2O ® ...............................................................................................
(1)
(iii)	Na2O + HCl ® ...............................................................................................
(2)
 
(b)	State and explain the trend in thermal stability of the carbonates of the Group 2 elements as the group is descended.
....................................................................................................................................
....................................................................................................................................
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(3)
(Total 7 marks)

7.	(a)	(i)	Calculate the number of moles of potassium nitrate, KNO3, in 10.1 g of KNO3.

(1)
 
(ii)	Potassium nitrate, KNO3, can be prepared from potassium hydroxide solution as shown in the following equation:
KOH(aq) + HNO3(aq) ® KNO3(aq) + H2O(l)
	Calculate the minimum volume, in cm3, of 2.00 mol dm–3 KOH required to produce 10.1 g of KNO3.

 
(2)

(iii)	Potassium nitrate decomposes, when heated, to produce oxygen.
2KNO3(s) ® 2KNO2(s) + O2(g)
	Calculate the volume of oxygen gas, in dm3, produced when 10.1 g of potassium nitrate decomposes in this way.
(1 mole of gas has a volume of 24 dm3 under the conditions of the experiment.)

(2)
 
(b)	A compound of potassium and oxygen contains 70.9% potassium.
(i)	Calculate the empirical formula of this compound, using the data above and the periodic table.

(3)

(ii)	0.200 moles of this compound has a mass of 22.0 g. Use this information to help you deduce the molecular formula of this compound.

(2)
(Total 10 marks)

8.	(a)	The first ionisation energy of potassium is +419 kJ mol–1 and that of sodium
is +496 kJ mol–1.
(i)	Define the term first ionisation energy.
………….……………….……………………………………………………..
………….……………….……………………………………………………..
………….……………….……………………………………………………..
(3)
 
(ii)	Explain why the first ionisation energy of potassium is only a little less than the first ionisation energy of sodium.
………….……………….……………………………………………………..
………….……………….……………………………………………………..
………….……………….……………………………………………………..
………….……………….……………………………………………………..
………….……………….……………………………………………………..
(3)

(b)	Potassium forms a superoxide, KO2. This reacts with carbon dioxide according to the equation:
4KO2(s) + 2CO2(g) ® 2K2CO3(s) + 3O2(g)
	Carbon dioxide gas was reacted with 4.56 g of potassium superoxide.
(i)	Calculate the amount, in moles, of KO2 in 4.56 g of potassium superoxide.

(2)
 
(ii)	Calculate the amount, in moles, of carbon dioxide that would react with 4.56 g of potassium superoxide.

(1)
 
(iii)	Calculate the volume of carbon dioxide, in dm3, that would react with 4.56 g of potassium superoxide. Assume that 1.00 mol of a gas occupies 24 dm3 under the conditions of the experiment.

(1)

(iv)	What volume of oxygen gas, in dm3, measured under the same conditions of pressure and temperature, would be released?

(1)
(Total 11 marks)

9.	In an experiment to show the migration of ions, silver(I) nitrate solution, AgNO3(aq), and potassium chromate(VI) solution, K2CrO4(aq), were used. The experiment was set up as shown in the diagram below. After a short while, a red precipitate formed in the centre of the filter paper.

(a)	Write the formulae, including charges, of the following ions:
(i)	Nitrate ions .......................................................................................................
(ii)	Chromate (VI) ions ..........................................................................................
(2)
 
(b)	Which ions would meet in the centre of the filter paper?
....................................................................................................................................
(1)

(c)	Write a balanced ionic equation, including state symbols, for the formation of the red precipitate.

(2)
(Total 5 marks)

10.	A compound A is formed when chlorine is bubbled through hot concentrated potassium hydroxide solution.
(a)	Analysis of A shows that it contains 31.84% potassium, 28.98% chlorine and the remainder is oxygen.
	Show that the empirical formula of A is KClO3

(3)

(b)	On being heated strongly solid A decomposes completely to give oxygen gas and solid potassium chloride.
2KClO3 ® 2KCl + 3O2
	If 1.00 g of solid A is decomposed completely in this way, calculate the volume of oxygen gas produced at room temperature and pressure.
	(One mole of a gas at room temperature and pressure occupies 24 dm3)

(3)
(Total 6 marks)

11.	(a)	(i)	Calculate the number of moles of sulphur atoms in 4.00 g of sulphur.

(1)
 
(ii)	When sulphur burns in air, it forms sulphur dioxide gas, SO2.
	What volume of sulphur dioxide, measured at room temperature and pressure, would be produced when 4.00 g of sulphur is burnt in air?
[Molar volume is 24 dm3 mol–1 at room temperature and pressure.]

(2)

(b)	Sulphur dioxide reacts with sodium hydroxide solution to form a solution of sodium sulphite, Na2SO3.
	The equation for the reaction is
SO2(g)  + 2NaOH(aq) → Na2SO3(aq) + H2O(l)
	Rewrite this equation as an ionic equation, omitting the spectator ions.
.....................................................................................................................................
(2)
(Total 5 marks)

12.	(a)	A 2.20 g sample of potassium nitrate, KNO3, was dissolved in water to produce 50.0 cm3 of potassium nitrate solution.
	Calculate the concentration of this solution in mol dm–3.

(2)

(b)	A 2.20 g sample of potassium nitrate was heated strongly and the following reaction occurred.
2KNO3(s) ® 2KNO2(s) + O2(g)
(i)	Calculate the mass of potassium nitrite, KNO2, produced.

(2)
 
(ii)	Calculate the volume of oxygen gas produced.
	(One mole of gas occupies a volume of 24.0 dm3 under the conditions of the experiment).

(2)
(c)	State and explain the trend in the thermal stability of the nitrates of Group I as the atomic number increases.
...............................................................................................................................................
...............................................................................................................................................
...............................................................................................................................................
...............................................................................................................................................
(3)
 
(d)	An analysis of a potassium compound gave the following results.
Element	Percentage by mass	
potassium	56.5%	
carbon	8.7%	
oxygen	34.8%	
	Deduce the empirical formula of this compound.

(3)
(Total 12 marks)

13.	How many nitrogen molecules, N2, are present in 12 dm3 of nitrogen gas at room temperature and pressure?
	[Molar volume is 24 dm3 mol–1 at room temperature and pressure;
Avogadro constant is 6 × 1023 mol–1]

(Total 2 marks)

14.	Copper(II) sulphate solution can be prepared from solid copper(II) carbonate by reaction with hot dilute sulphuric acid.
(a)	Write the balanced equation for this reaction, including state symbols.

(2)
 
(b)	This experiment was carried out using 25 cm3 of 1.0 mol dm–3 sulphuric acid.
(i)	How would you measure out 25 cm3 of 1.0 mol dm–3 sulphuric acid?
...........................................................................................................................
(1)
(ii)	Calculate the number of moles of sulphuric acid used.

(1)

(c)	(i)	It is usual to react the sulphuric acid with a slight excess of copper(II) carbonate.
Calculate the mass of copper(II) carbonate needed if a 10 % excess is required.
[Molar mass of copper(II) carbonate = 123.5 g mol–1]

(2)
 
(ii)	The sulphuric acid is heated to boiling and the copper(II) carbonate is added in small portions.
	Suggest why the copper(II) carbonate is added in small portions.
...........................................................................................................................
...........................................................................................................................
(1)
(iii)	What would be the next step needed to obtain pure copper(II) sulphate solution?
...........................................................................................................................
...........................................................................................................................
(1)
 
(d)	3.98 g of copper(II) sulphate-5-water, CuSO4.5H2O, was obtained from this solution.
(i)	Calculate the molar mass of copper(II) sulphate-5-water.
Use the Periodic Table as a source of data.

(1)
 
(ii)	Calculate the percentage yield of the reaction.

(2)
 
(e)	Suggest why copper compounds are hazardous.
......................................................................................................................................
(1)
(Total 12 marks)

15.	Phosphorus(III) chloride, PCl3, can be formed by the reaction of phosphorus and chlorine.
2P(s)  + 3Cl2(g)  ®  2PCl3(s)
(a)	(i)	Calculate the maximum mass of phosphorus(III) chloride, PCl3, which could be obtained from 93.0 g of phosphorus.

(3)

(ii)	Calculate the minimum volume of chlorine required to react completely with 93.0 g of phosphorus.
[One mole of gas occupies a volume of 24.0 dm3 under the conditions of the experiment].

(2)
 
(iii)	Identify the oxidising agent in the above reaction and explain your answer.
.....................................................................................................................................
.....................................................................................................................................
(2)
 
(b)	(i)	Draw a dot and cross diagram for a molecule of PCl3.

(2)

(ii)	Draw the predicted shape of a PCl3 molecule and mark on the diagram a value for the bond angle.

(2)
 
(c)	Suggest the name for the shape of the PCl4+ ion.
...............................................................................................................................................
(1)
(Total 12 marks)

16.	(a)	(i)	Write the ionic half-equation to show the oxidation of calcium, Ca, to calcium ions, Ca2+.
.....................................................................................................................................
(1)
 
(ii)	Write the ionic half-equation to show the reduction of water to hydrogen, H2, and hydroxide ions, OH–.
.....................................................................................................................................
(1)
 
(iii)	Combine the two ionic half-equations above to produce an equation which shows the effect of adding calcium to water.
.....................................................................................................................................
(1)
 
(iv)	State what you would expect to see when calcium is added to water.
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
(2)
 
(b)	State the trend in solubility of the hydroxides of the Group 2 elements as the atomic number increases.
.....................................................................................................................................
(1)
 
(c)	Write an equation to show the reaction between sodium and chlorine, to produce sodium chloride.
.....................................................................................................................................
(2)
(Total 8 marks)

17.	Balance this equation showing how magnesium nitrate decomposes when heated.
Mg(NO3)2(s)   ®   MgO(s)   +   NO2(g)   +   O2(g)
(Total 1 mark)

18.	(a)	Define the term reduction.
.......................................................................................................................................
.......................................................................................................................................
(1)

(b)	Sodium iodide, NaI, contains iodide ions which reduce Fe3+ ions to Fe2+ ions in aqueous solution.
(i)	Write the ionic half-equation for the reduction of Fe3+ ions to Fe2+ ions.
................................................................................................................................
(ii)	Write the ionic half-equation for the oxidation of iodide ions.
................................................................................................................................
(1)
(iii)	Hence write the overall ionic equation for the reduction of Fe3+ ions by iodide ions.
................................................................................................................................
(1)
 
(c)	Sodium chlorate, NaClO3, is used as a weedkiller and is manufactured by the following disproportionation reaction
3NaClO ® 2NaCl + NaClO3
(i)	State the oxidation numbers of chlorine in
NaClO ..................................................................
NaClO3 ..................................................................
NaCl   ..................................................................
(3)
 
(ii)	Explain why this reaction is classified as a disproportionation reaction. 
................................................................................................................................
................................................................................................................................
................................................................................................................................
(1)

(d)	The decomposition of sodium azide, NaN3, takes place when an airbag, which is used as a safety feature in cars, inflates. An airbag requires a large volume of a cool gas to be produced in a few milliseconds. The gas is produced by the rapid decomposition of the sodium azide.
2NaN3(s) ® 2Na(l) + 3N2(g)
	When the airbag is fully inflated, 54 dm³ of nitrogen gas are produced.
(i)	Calculate the amount (in moles) of nitrogen gas produced.
	[The molar volume of nitrogen gas under the conditions in the airbag is 20 dm³ mol–1].

(1)
 
(ii)	Calculate the amount (in moles) of sodium azide, NaN3, that would produce 54 dm³ of nitrogen gas.

(1)
 
(iii)	Calculate the mass of sodium azide that would produce 54 dm³ of nitrogen gas.

(2)
(Total 12 marks)

19.	Calculate the volume, measured at room temperature and pressure, of the following masses of gases.
	Use the Periodic Table as a source of data.
	[Molar volume of a gas is 24 dm3 at room temperature and pressure.]
(a)	4 g of helium, He.

..........................
(1)
(b)	4 g of hydrogen, H2.

..........................
(1)
(Total 2 marks)

20.	This question is about ammonium dichromate(VI), (NH4)2Cr2O7(s), which is slightly soluble in water. Ammonium dichromate(VI) can be prepared by the following reaction:
Na2Cr2O7(aq) + 2NH4NO3(aq) ® (NH4)2Cr2O7(s) + 2NaNO3(aq)
(a)	What type of reaction is this?
......................................................................................................................................
(1)
 
(b)	(i)	Give the formulae of the ions present in ammonium dichromate(VI).
...............................................................................................................................
(2)
(ii)	Re-write the equation as an ionic equation, but omit any spectator ions.

(1)

(iii)	An orange crystal of ammonium dichromate(VI) was placed in the centre of a piece of moist filter paper supported on a glass microscope slide.

	Describe what you would expect to see when electricity is passed through the circuit.
...............................................................................................................................
(1)
 
(c)	(i)	Calculate the mass of 1 mole of ammonium dichromate(VI). Use the Periodic Table as a source of data.

(1)
 
(ii)	In an experiment to prepare ammonium dichromate(VI), 0.1 mol of sodium dichromate(VI) was used.
	What is the maximum mass of ammonium dichromate(VI) which could be obtained?

(1)

(iii)	What volume of ammonium nitrate solution of concentration 2 mol dm–3 would react exactly with 0.1 mol of sodium dichromate(VI)?

(1)
 
(iv)	Describe how you would obtain pure, dry crystals of ammonium dichromate(VI) from the resultant mixture.
...............................................................................................................................
...............................................................................................................................
...............................................................................................................................
...............................................................................................................................
...............................................................................................................................
(3)
 
(v)	Suggest TWO reasons why the mass of ammonium dichromate(VI), prepared in this way, is likely to be less than the mass calculated in (ii).
...............................................................................................................................
...............................................................................................................................
...............................................................................................................................
...............................................................................................................................
(2)
(Total 13 marks)

21.	(a)	(i)	Potassium superoxide contains 54.9 % potassium by mass.
Show that the empirical formula of this compound is KO2.

(3)
 
(ii)	Give the oxidation number of oxygen in the compound KO2.
............................................................................................................................
(1)

(b)	Which of potassium nitrate or lithium nitrate has the higher thermal stability?
Explain your answer.
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(3)
(Total 7 marks)

22.	Silicon reacts with chlorine to produce silicon tetrachloride, as shown in the following equation
Si(s) + 2Cl2(g) → SiCl4(l)
(a)	(i)	Calculate the mass of silicon tetrachloride obtained from 10.0 g of silicon.

(3)

(ii)	Calculate the minimum volume of chlorine that would be required to react completely with 10.0 g of silicon.
	[1 mol of gas occupies 24.0 dm3 under the conditions of the experiment]

(2)

(b)	Draw a silicon tetrachloride molecule, SiCl4, showing its three-dimensional shape.
Name the shape and state the bond angle. Explain why the molecule has this shape.
	Diagram

	Name of shape .............................................................................................................
	Bond angle ..............................................
	Explanation of shape
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
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(5)
 
(c)	(i)	Why are silicon-chlorine bonds polar?
............................................................................................................................
............................................................................................................................
(1)

(ii)	Explain why the silicon tetrachloride molecule has no permanent dipole.
............................................................................................................................
............................................................................................................................
............................................................................................................................
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(2)
(Total 13 marks)

23.	(a)	Barium carbonate can be converted into barium chloride solution by a reaction with hydrochloric acid. In a particular experiment, an excess of barium carbonate was added to 25 cm3 of hydrochloric acid of concentration 1.0 mol dm–3.
(i)	Describe how you would obtain dry crystals of hydrated barium chloride, BaCl2.2H2O, from the reaction mixture.
................................................................................................................................
................................................................................................................................
................................................................................................................................
................................................................................................................................
................................................................................................................................
................................................................................................................................
................................................................................................................................
(4)
 
(ii)	Write a balanced equation, including state symbols, for this reaction.

(2)

(iii)	Calculate the number of moles of hydrochloric acid used in the experiment.

(1)
 
(iv)	Calculate the mass of one mole of hydrated barium chloride, BaCl2.2H2O. Use the Periodic Table as a source of data.

(1)
 
(v)	Calculate the theoretical mass of crystals which could be obtained.

(1)
 
(vi)	Suggest a reason why this mass of crystals is unlikely to be obtained in practice.
................................................................................................................................
................................................................................................................................
................................................................................................................................
(1)
 
(b)	(i)	What colour do barium compounds produce in a flame test?
................................................................................................................................
(1)
(ii)	When carrying out a flame test on a solid, state a suitable material on which it can be supported in the flame.
................................................................................................................................
(1)
(Total 12 marks)

24.	(a)	Sodium chloride, NaCl, can be made by the reaction of sodium with chlorine.
2Na(s) + Cl2(g) ® 2NaCl(s)
(i)	Calculate the maximum mass of sodium chloride which could be obtained from 92 g of sodium.

(2)
 
(ii)	Calculate the concentration of the solution obtained when this mass of sodium chloride is dissolved in water and made up to a volume of 10 dm3 with distilled water.

(1)
 
(iii)	Calculate the volume of chlorine gas required to react with 92 g of sodium.
	[1 mol of gas occupies 24 dm3 under the conditions of the experiment]

(2)

(b)	Describe the structure of solid sodium metal and explain why it conducts electricity.
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
(3)
 
(c)	(i)	Define the term first ionisation energy.
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
(3)
 
(ii)	Explain why the first ionisation energy of chlorine is higher than that of sodium.
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
(2)
(Total 13 marks)

25.	(a)	Calculate the number of atoms in 3.50 g of lithium.
	Use the Periodic Table as a source of data.
	[The Avogadro constant, L = 6.02 × 1023 mol–1]

(2)
 
(b)	The equation for the reaction of lithium with hydrochloric acid is shown below.
2Li(s) + 2HCl(aq) ® 2LiCl(aq) + H2(g)
(i)	Rewrite this equation as an ionic equation, omitting the spectator ions.

(1)

(ii)	Draw a ‘dot and cross’ diagram of lithium chloride showing all the electrons. Indicate charges clearly on your diagram.

(2)
 
(iii)	The value of the standard enthalpy change for the reaction, DHο, is –557 kJ mol–1. State TWO of the reaction conditions necessary for this enthalpy change to be standard.
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
(2)
(Total 7 marks)

26.	(a)	Sodium iodide reacts with chlorine to produce sodium chloride and iodine.
(i)	State the oxidation numbers of the iodine and chlorine species in the spaces provided.
	2NaI	+	Cl2	→	2NaCl	+	I2
	..........		..........		..........		.........
(2)
 
(ii)	Use these oxidation numbers to explain why this reaction is a redox reaction.
...........................................................................................................................
...........................................................................................................................
(2)
 
(iii)	Calculate the maximum mass of iodine that could be produced from 30.0 g of sodium iodide.

(3)
 
(iv)	Calculate the volume of chlorine gas required to produce this amount of iodine.
	[1 mol of gas occupies 24 dm3 under the conditions of the experiment]

(1)

(b)	(i)	Give the colour of iodine and its physical state at room temperature and pressure.
Colour ........................................................................................
Physical state .............................................................................
(2)
 
(ii)	Write an equation, including state symbols, to represent the process occurring when the first ionisation energy of iodine atoms is measured.
...........................................................................................................................
(2)
(Total 12 marks)

27.	(a)	(i)	Explain why a water molecule does not have a linear shape.
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
(2)
 
(ii)	State the HOH bond angle in water and explain why it has this value.
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
(2)

(b)	(i)	Draw the boron trichloride molecule, BCl3, making its shape clear. Mark in the bond angle on your diagram.

(2)
 
(ii)	Explain why a B–Cl bond is polar.
...........................................................................................................................
...........................................................................................................................
(1)
 
(iii)	Explain why a BCl3 molecule is non-polar.
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
(1)
 
(iv)	Name the strongest intermolecular force between boron trichloride molecules.
...........................................................................................................................
...........................................................................................................................
(1)
 
(c)	A compound of phosphorus and chlorine has the composition by mass shown below.
Element	% by mass	
P	14.9	
Cl	85.1	
	Calculate the empirical formula of this compound.

(2)
(Total 11 marks)

28.	A metal carbonate decomposes on heating to give an oxide and carbon dioxide.
XCO3(s) ® XO(s) + CO2(g)
	where X is the metallic element.
	In an experiment to find the identity of X, 5.75 g of the solid XCO3 was heated until there was no further change in mass; 3.55 g of solid XO was produced.
(a)	Explain why it was necessary to heat the carbonate until there was no further change 	in mass.
.....................................................................................................................................
.....................................................................................................................................
(1)
 
(b)	(i)	Calculate the mass of carbon dioxide gas given off.

(1)

(ii)	Calculate the amount (moles) of carbon dioxide gas given off.

(1)
 
(iii)	Use the answer from (ii) to state the amount (moles) of XCO3 in 5.75 g of the
solid.
...........................................................................................................................
(1)
 
(iv)	Calculate the molar mass of XCO3.

(1)
 
(v)	Use your answer from (iv) and the relative atomic masses of carbon and oxygen to calculate the relative atomic mass of X in XCO3.

(1)

(c)	All measurements of mass have some uncertainty. In this case, this leads to an error of ±0.91 % in the molar mass of XCO3.
(i)	Use this information and your answer to (b)(iv) to calculate the error in the molar mass of XCO3.

(1)
 
(ii)	Hence suggest the range of possible values for the molar mass of XCO3.
...........................................................................................................................
(1)
 
(iii)	Hence give the range of possible values of the relative atomic mass of X.

(1)

(iv)	Use the Periodic Table and your answer to (c)(iii) to suggest possible identities of metal X.
...........................................................................................................................
...........................................................................................................................
(1)
(Total 10 marks)

29.	(a)	The mass of one atom of the isotope  is 1.31 × 10–22 g. The molar mass of  is 79.0 g mol–1.
	Use this information to calculate a value for the Avogadro constant. Give your answer to three significant figures.

(2)

(b)	According to the Periodic Table, the relative atomic mass of naturally occurring bromine is 80.
	What information can you deduce from this about naturally occurring bromine?
(No calculation is expected.)
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
(1)
(Total 3 marks)

30.	(a)	Complete the table below which is about isotopes and an ion of magnesium.
	Numbers of	
	Protons	Neutrons	Electrons	
	12	12		
	12		12	
	12	12		
(3)
 
(b)	Complete the electronic configurations of magnesium and chlorine atoms.
		1s	2s	2p	3s	3p
Mg	↓↑		↓↑											
(1)
		1s	2s	2p	3s	3p
Cl	↓↑		↓↑											
(1)
 
(c)	Write the equation, including state symbols, for the reaction of magnesium with chlorine.
.....................................................................................................................................
(2)

(d)	The mass spectrum of a sample of chlorine molecules shows three molecular peaks.
These are formed from the molecules shown below.
Molecule	Percentage abundance	
35Cl-35Cl	56.25	
35Cl-37Cl	37.50	
37Cl-37Cl	6.25	
	Calculate the relative molecular mass of chlorine in this sample.

(2)
 
(e)	Calculate the volume of 4.73 g of chlorine gas at 100 °C.
	[The molar volume of a gas at 100 °C = 30.6 dm3 mol–1]

(2)
 
(f)	State and explain the type of bond that exists in solid magnesium.
Type ..............................................................
Explanation  ................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
(3)
 
(g)	State the type of bond that exists in magnesium chloride. Draw a dot and cross diagram showing the outer shell electrons.
Type ..............................................................
Dot and cross diagram

(3)
(Total 17 marks)

31.	Sodium azide, NaN3, is used to inflate air bags in cars because, in a collision, the sodium azide decomposes rapidly to produce nitrogen gas.
	2NaN3(s) ® 2Na(s) + 3N2(g)
(a)	(i)	Calculate the mass of one mole of sodium azide, NaN3.
Use the Periodic Table as a source of data.

(1)

(ii)	What mass of sodium azide would be needed to liberate 48 dm3 of nitrogen?
[Molar volume of a gas is 24 dm3 mol–1 at room temperature and pressure]

(2)
(b)	What safety problem would arise when disposing of the air bag after a collision?
Justify your answer.
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
(2)
(Total 5 marks)

32.	This question is about the chemistry of propane, C3H8.
	Propane is sold for use as a fuel for camping stoves. On complete combustion it forms carbon dioxide and water.
(a)	The enthalpy change of combustion of propane, ΔHc, can be measured by burning a known mass of propane below a container of water and measuring the temperature rise of the water.
	The heat capacity of the apparatus (the energy required to raise the temperature of the apparatus by 1 °C) is found by calibrating it with a fuel with known enthalpy change of combustion.
	The results of an experiment are shown below.
	Mass of propane burned	0.500 g
Temperature of water at start	21.0 °C
Final temperature of water	39.0 °C
Heat capacity of apparatus	1.35 kJ °C–1
 
(i)	Calculate the number of kilojoules of energy transferred when the 0.500 g sample of propane burns in this experiment.
(1)
 
(ii)	Use your answer to (i) to calculate ΔHc for propane in kJ mol–1. Give your answer to three significant figures.
	Use the Periodic Table as a source of data.

(2)
(iii)	The Book of data gives the value of ΔHc for propane as –2220 kJ mol–1.
	Calibrating the apparatus means that the answer you calculated in (ii) allows for errors due to heat loss.
	Suggest the other main source of error which makes the experimental result different from the data book value.
...........................................................................................................................
...........................................................................................................................
(1)

(b)	A value of ΔHc for propane can be calculated using mean bond energies and the Hess cycle below.
(i)	Complete the Hess cycle, and use the mean bond energies to calculate ΔH1.
Hence calculate ΔHc.
	Mean bond energies
/kJ mol–1	
C=O	805	
H–O	464	

ΔHc = ................................................................................................................
(3)
 
(ii)	Give ONE reason why the value you calculated in (b)(i) also differs from the value for the heat of combustion of propane in the Book of data.
...........................................................................................................................
...........................................................................................................................
(1)
 
(c)	When propane reacts with chlorine in the presence of ultraviolet light one of the products is 2-chloropropane.
(i)	Name the mechanism and type of this reaction.
Mechanism .......................................................................................................
Type ..................................................................................................................
(2)
 
(ii)	In this reaction a small quantity of an alkane, C6H14, is produced.
	Explain how this occurs. Include an equation in your answer.
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
(2)
 
(d)	2-Chloropropane and 2-iodopropane are both colourless liquids at room temperature.
They can be distinguished by their reactions with aqueous silver nitrate.
(i)	What would you see when the reaction is carried out with each halogenoalkane?
2-chloropropane ...............................................................................................
2-iodopropane ..................................................................................................
(2)
 
(ii)	Write an ionic equation showing how silver ions react in the mixture made from 2-iodopropane and aqueous silver nitrate. Include state symbols in your answer.

(2)
 
(iii)	Both 2-chloropropane and 2-iodopropane form the same organic product in the reaction with aqueous silver nitrate.
	Name, or give the structural formula of, this organic product.
...........................................................................................................................
(1)
(Total 17 marks)

33.	(a)	Define the term Avogadro constant.
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
(2)
 
(b)	Z is a Group 0 element.
(i)	1.907g of Z contains 2.87 × 1022 atoms of Z.
	Calculate the relative atomic mass of Z.
[Avogadro constant = 6.02 × 1023 mol–1]

(2)
 
(ii)	Suggest the identity of Z.
................................................................
(1)

(c)	Potassium superoxide, KO2, reacts with water as follows:
	2KO2(s) + 2H2O(l) → 2KOH(aq) + H2O2(aq) + O2(g)
(i)	Calculate the mass of potassium superoxide needed to produce 3.09 g of hydrogen peroxide.
	[Molar mass of potassium superoxide, KO2: 71g mol–1. Molar mass of hydrogen peroxide, H2O2 : 34 g mol–1]

(3)
(ii)	Calculate the volume of oxygen produced from the reaction in (i).
	[Molar volume of oxygen under the conditions of the reaction = 24.0 dm3 mol–1]

(1)
(Total 9 marks)

34.	25.0 cm3 of a solution contains 0.020 mol of ethanoic acid.
	Calculate its concentration in mol dm–3.

(Total 1 mark)

35.	Nickel is one of the elements in the d-block of the Periodic Table.
(a)	Complete the electron configuration of a nickel atom using the s, p, d notation.
	Use the Periodic Table as a source of data.
1s2 ...............................................................................................................................
(2)

(b)	A sample of nickel consists of three isotopes. Their percentage abundances are shown in the table below.
Isotope	Percentage Abundance	
58Ni	69.02	
60Ni	27.32	
62Ni	3.66	
	Calculate the average relative atomic mass of nickel.

(2)
 
(c)	Nickel reacts with carbon monoxide to give the compound nickel carbonyl, Ni(CO)4.
	Ni(s) + 4CO(g) → Ni(CO)4(g)
	Calculate the volume of carbon monoxide required to react completely with 5.9 g of nickel.
	Use the Periodic Table as a source of data.
[The molar volume of a gas is 24 dm3 mol–1 at room temperature and pressure.]

(2)

(d)	Finely powdered nickel reacts slowly with dilute sulphuric acid to form a solution of nickel(II) sulphate.
	Ni(s) + H2SO4(aq) → NiSO4(aq) + H2(g)
(i)	Re-write this equation in an ionic form, omitting the spectator ion. State symbols are not required.

(1)
 
(ii)	A sample of finely powdered nickel is added to a slight excess of dilute sulphuric acid.
	Describe the practical steps you would take to obtain dry crystals of hydrated nickel(II) sulphate from the mixture, after the reaction is complete.
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
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(3)

(iiii)	Calculate the maximum mass of hydrated nickel(II) sulphate, NiSO4.7H2O, which could be formed from 2.95 g of nickel.

(2)
(Total 12 marks)

36.	(a)	Cooking fuels and petrol for car engines need to be gases or liquids which vaporise easily. This will be the case if the intermolecular forces are weak.
	Two common fuels are methane, CH4, and 2,2,4-trimethylpentane, C8H18.
	Electronegativity	
carbon	2.1	
hydrogen	2.5	
 
(i)	Explain the meaning of the term electronegativity.
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
(2)

(ii)	The C—H bond in methane has some polarity but overall the molecule is non-polar.
	Explain why methane is a non-polar molecule.
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
(2)
 
(iii)	Identify the strongest intermolecular force that exists between
2,2,4-trimethylpentane molecules in the liquid state.
...........................................................................................................................
(1)
 
(b)	In a car engine 2,2,4-trimethylpentane burns in air to produce carbon dioxide and water.
	The equation is
	2C8H18 + 25O2 → 16CO2 + 18H2O
	Molar mass of C8H18 = 114 g mol–1
 
(i)	Calculate the volume of oxygen needed to burn 700 g of 2,2,4-trimethylpentane.
[Assume the molar volume of a gas = 24.0 dm3 mol–1]

(3)

(ii)	Calculate the mass of carbon dioxide produced in the reaction in (i).

(2)
(Total 10 marks)

37.	Phosphorus reacts with excess chlorine to produce phosphorus pentachloride, PCl5.
	2P(s) + 5Cl2(g) → 2PCl5(s)
(i)	Calculate the mass of phosphorus needed to produce 7.19 g of phosphorus pentachloride.

(2)
 
(ii)	Calculate the volume of chlorine needed to produce 7.19 g of phosphorus pentachloride.
	[molar volume of chlorine under the conditions of this experiment = 24.0 dm3 mol–1]

(2)
(Total 4 marks)

38.	This question is about the following equations:
A	Cu(NO3)2(s) ® CuO(s) + 2NO2(g) + O2(g)
B	2HCl(aq) + CuO(s) ® H2O(l) + CuCl2(aq)
C	C4H9OH(l) + 6O2(g) ® 4CO2(g) + 5H2O(l)
D	C8H18(l) + 8½O2(g) ® 8CO(g) + 9H2O(l)
(a)	Which equation is not balanced?
A
B
C
D
(1)
 
(b)	Which equation shows incomplete combustion?
A
B
C
D
(1)
(Total 2 marks)

39.	This question is about four hydrocarbons with molecular formulae as shown.
A	C2H2
B	C3H6
C	C3H8
D	C4H10

(a)	Which hydrocarbon has the same empirical formula as its molecular formula?
A
B
C
D
(1)
 
(b)	Which has a molecular ion in the mass spectrum at mass/charge ratio = 58?
A
B
C
D
(1)
 
(c)	Which is neither an alkane nor an alkene?
A
B
C
D
(1)
 
(d)	Which could be 2-methylpropane?
A
B
C
D
(1)
(Total 4 marks)

40.	This question is about magnesium and magnesium oxide.
(a)	Describe the bonding in magnesium and explain why it is a good conductor of electricity.
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
(3)
 
(b)	Draw a diagram (using dots or crosses) for the ions in magnesium fluoride showing all the electrons and the ionic charges on:
(i)	the magnesium ion

(1)
(ii)	the fluoride ion.

(1)
 
(c)	Under what conditions does magnesium fluoride conduct electricity?
	Explain your answer.
.....................................................................................................................................
.....................................................................................................................................
(1)

(d)	The mass spectrum of a sample of magnesium is shown below.

(i)	Use the data above to estimate the percentage isotopic composition of the sample of magnesium. Hence calculate the average atomic mass of the sample of magnesium.

(2)
 
(ii)	Why do the three isotopes have the same chemical properties?
...........................................................................................................................
...........................................................................................................................
(1)
 
(e)	(i)	Oceanographers studying plankton found that a sample of seawater contained 1.20 nanomol dm–3 of chlorophyll, C55H77MgN4O5. (1 nanomol = 1 × 10–9 mol)
	What mass of magnesium would be present in 1.00 cm3 of this sample of seawater? Give your answer to three significant figures.

(2)
(ii)	X-ray diffraction can be used to locate atoms or ions in molecules like chlorophyll.
X-rays are scattered by the electrons in atoms and ions. In chlorophyll the atoms of one of the elements still cannot be located with certainty by this technique.
	Suggest which element is most difficult to locate.
...........................................................................................................................
...........................................................................................................................
(1)
(Total 12 marks)

41.	Airbags, used as safety features in cars, contain sodium azide, NaN3. An airbag requires a large volume of gas to be produced in a few milliseconds. The gas is produced in this reaction:
	2NaN3(s) ® 2Na(s) + 3N2(g)	DH is positive
	When the airbag is fully inflated, 50 dm3 of nitrogen gas is produced.

(a)	Calculate the number of molecules in 50 dm3 of nitrogen gas under these conditions.
	[The Avogadro constant = 6.02 × 1023 mol–1. The molar volume of nitrogen gas under the conditions in the airbag is 24 dm3 mol–1].

(2)
 
(b)	Calculate the mass of sodium azide, NaN3, that would produce 50 dm3 of nitrogen gas.

(3)
 
(c)	What will happen to the temperature in the airbag when the reaction occurs?
.....................................................................................................................................
.....................................................................................................................................
(1)

(d)	The airbag must be strong enough not to burst in an accident. An airbag which has burst in an accident is hazardous if the sodium azide in it has decomposed.
	Explain why this is so.
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
(2)
(Total 8 marks)

42.	The volume, in cm3, of 0.25 mol dm–3 hydrochloric acid required to neutralise 100 cm3 of 0.125 mol dm–3 barium hydroxide solution, Ba(OH)2(aq), is
A	25
B	50
C	100
D	200
(Total 1 mark)