SECTION A: Multiple choice
1.
2.
3.
1
4.
5.
6.
7.
2
8.
9.
10.
3
11.
12.
13.
14.
4
15.
16.
17.
5
18.
19.
20.
6
SECTION B
1. (M08/TZ1) The value of x in Fe(NH4)2 (SO4)2. xH2O can be found by determining the amount, in
moles, of sulfate in the compound. A 0.982 g sample was dissolved in water and excess BaCl2(aq)
was added. The precipitate of BaSO4 was separated and dried and found to weigh 1.17 g.
(a) Calculate the amount, in moles of BaSO4 in the 1.17 g precipitate.
[2]
(b) Calculate the amount, in moles, of sulfate in the 0.982 g sample of Fe(NH4)2(SO4)2.xH2O [1]
(c) Calculate the amount, in moles, of iron in the 0.982 g sample of Fe(NH4)2 (SO4)2. xH2O. [1]
(d) Determine the mass of the following present in the 0.982 g sample of Fe(NH4 )2 (SO4)2. xH2O.[3]
(i) iron
(ii) ammonium
(iii) sulfate
(e) Use your answer from part (d) to determine the amount, in moles, of water present in the
0.982g sample of Fe(NH4 )2 (SO4 )2. X H2O.
(f) Determine the amount, in moles, of Fe(NH4)2 (SO4 )2 and hence the value of x.
[2]
[2]
2. (M08/TZ2)
(a) A 25.0 cm3 sample of an aqueous solution of barium hydroxide, of concentration 0.146 mol dm−3
was exactly neutralized by 28.7 cm3 of aqueous nitric acid, according to the following equation.
Ba(OH)2 (aq) + 2HNO3 (aq) → Ba(NO3)2 (aq) + 2H2O (l)
Calculate the concentration (in mol dm−3) of the nitric acid.
[3]
(b) A solution containing 0.142 mol aqueous nitric acid was added to a solution containing 0.107 mol
barium hydroxide. Calculate the amount (in mol) of barium nitrate formed.
[1]
(c) A 0.010 mol sample of the barium nitrate formed was heated until it had completely decomposed
according to the following equation.
2Ba(NO3)2 (s) → 2BaO(s) + 4NO2 (g) + O2 (g)
Use the ideal gas equation to calculate the total volume, in cm3, of gaseous products obtained at
387 K and1.12×105 Pa.
[3]
3. (N07) 0.502 g of an alkali metal sulfate is dissolved in water and excess barium chloride
solution, BaCl2(aq) is added to precipitate all the sulfate ions as barium sulfate, BaSO4 (s). The
precipitate is filtered and dried and weighs 0.672 g.
(a) Calculate the amount (in mol) of barium sulfate formed.
[2]
(b) Determine the amount (in mol) of the alkali metal sulfate present.
[1]
(c) Determine the molar mass of the alkali metal sulfate and state its units.
[2]
(d) Deduce the identity of the alkali metal, showing your workings.
[2]
(e) Write an equation for the precipitation reaction, including state symbols.
[2]
7
4. (M07)
(a) Crocetin consists of the elements carbon, hydrogen and oxygen. Determine the empirical
formula of crocetin, if 1.00 g of crocetin forms 2.68 g of carbon dioxide and 0.657 g of water
when it undergoes complete combustion.
[6]
(b) Determine the molecular formula of crocetin given that 0.300 mole of crocetin has a mass of
98.5 g.
[2]
8
9
Mark scheme
SECTION A
1
2
3
4
5
A
B
B
D
C
6
7
8
9
10
B
D
B
C
D
11
12
13
14
15
D
C
B
C
C
16
17
18
19
20
A
C
C
C
C
SECTION B
1.
2.
10
3
11
4.
12