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GCSE
Answer all questionsAnswer questions in the space providedAll working must be shownDo all rough work in this book. Cross out any rough work you don't want to be marked
Score (%)Mark
MaterialsFor this paper you must have:
RulerPencil, Rubber, Protractor and CompassScientific calculator, which you are expected to use when appropriate
Instructions
InformationThe marks for the questions are shown in brackets
Name:
Date:
AQA - COMBINED SCIENCE
www.ExamQA.com
CHEMISTRY
C3
QUANTITATIVE CHEMISTRY
TEST 2
Formulae and equations are used to describe chemical reactions.
(a) Aluminium reacts with sulfuric acid (H2SO4) to produce aluminium sulfate, Al2(SO4)3 andhydrogen (H2).
Complete and balance the equation for this reaction.
____Al + _____________ _____________ + ____________
(2)
1
(b) Calcium carbonate reacts with nitric acid to produce calcium nitrate.
Calculate the relative formula mass (Mr) of calcium nitrate, Ca(NO3)2
Relative atomic masses (Ar): N = 14; O = 16; Ca = 40
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Relative formula mass (Mr) = __________________
(2)
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(c) Zinc carbonate decomposes when heated.
A student heated 25 g zinc carbonate (ZnCO3).
The figure below shows how he set up the apparatus.
The balanced chemical equation for the decomposition reaction is:
ZnCO3 (s) ZnO (s) + CO2 (g)
The student measured the mass of solid product after heating until there was no furtherchange in mass.
The student did the experiment four times. The table below shows the results.
Experiment 1 2 3 4
Mass of solid product in g 17.4 19.7 17.6 16.9
Calculate the mean mass of the solid product.
Do not use any anomalous results in your calculation.
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Mean mass = _________________ g
(2)
(Total 6 marks)
Bromine can be made from sea water. In 1000 g of sea water there is 0.065 g of bromine.What mass of sea water would be needed to make 1000 g of bromine?
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(Total 2 marks)
2
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(a) Some students did an experiment to find the temperature change when hydrochloric acidreacts with sodium hydrogencarbonate.
The results are in the table.
Number of spatulameasures of sodiumhydrogencarbonate
Start temperaturein °C
Final temperaturein °C
Change intemperature in °C
2 20 16 4
4 20 14 6
6 19 11 8
8 20 10 10
10 19 9 10
12 20 10 10
(i) Describe, as fully as you can, the trends shown in the students’ results.
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(3)
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(ii) State the type of energy transfer for this reaction.
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(1)
(b) Sodium hydrogencarbonate is used as baking powder for making cakes.
When the cake mixture is baked the sodium hydrogencarbonate decomposes.
The equation for the reaction is:
(i) The cake mixture rises when baked.
© Michael Valdez/iStock
Use the equation to suggest why.
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(1)
(ii) The same reaction can be reversed to produce sodium hydrogencarbonate fromsodium carbonate.
Na2CO3 + H2O + CO2 2NaHCO3
Do the reactants need to be heated?
Give a reason for your answer.
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(1)
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(c) (i) Calculate the relative formula mass of sodium hydrogencarbonate (NaHCO3).
Relative atomic masses (Ar): H=1; C=12; O=16; Na=23
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Relative formula mass (Mr) = ______________________
(2)
(ii) Calculate the percentage by mass of carbon in sodium hydrogencarbonate.
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Percentage of carbon = _________________________ %
(1)
(Total 9 marks)
Toothpastes often contain fluoride ions to help protect teeth from attack by bacteria.
Some toothpastes contain tin(II) fluoride.
This compound has the formula SnF2 .
4
(a) Calculate the relative formula mass (Mr) of SnF2.
Relative atomic masses: F = 19; Sn = 119
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Relative formula mass (Mr) = _____________________
(2)
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(b) Calculate the percentage by mass of fluorine in SnF2.
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Percentage by mass of fluorine = _____________________ %
(2)
(c) A tube of toothpaste contains 1.2 g of SnF2.
Calculate the mass of fluorine in this tube of toothpaste.
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Mass of fluorine = _____________________ g
(1)
(d) The diagram represents the electron arrangement of a fluorine atom.
Explain how a fluorine atom can change into a fluoride ion, F–.
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(2)
(Total 7 marks)
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Figure 1 shows a reactor used to produce titanium from titanium(IV) chloride.
Figure 1
The chemical equation for the reaction of titanium(IV) chloride with sodium is:
TiCl4 + 4Na Ti + 4NaCl
titanium(IV) chloride + sodium titanium + sodium chloride
(a) For one reaction:
• 1615 kg titanium(IV) chloride reacted completely with 782 kg sodium• 1989 kg sodium chloride was produced.
Calculate the mass of titanium produced from this reaction.
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Mass of titanium = _________________ kg
(1)
5
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(b) The table below shows the solubility of sodium chloride in 100 cm3 of aqueous solution atdifferent temperatures.
Solubility of sodium chloride in g per100cm3
Temperature in °C
35.72 10
35.89 20
36.09 30
37.37 40
36.69 50
37.04 60
On Figure 2:
• plot this data on the grid• draw a line of best fit.
Figure 2
(3)
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(c) The product sodium chloride is dissolved in water to separate it from titanium.
At 30 °C the solubility of sodium chloride is 36 kg per 100 dm3.
Calculate the minimum volume of water in dm3, at 30 °C, needed to dissolve 1989 kgsodium chloride.
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Volume of water = ____________________ dm3
(2)
(d) Calculate the percentage by mass of titanium in titanium(IV) chloride (TiCl4).
Give your answer to 3 significant figures.
Relative atomic masses (Ar): Cl = 35.5; Ti = 48
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Percentage of titanium by mass = _______________ %
(3)
(e) Suggest why the reaction is done in an atmosphere of dry argon instead of air containingwater vapour.
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(3)
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(f) Explain why titanium conducts electricity.
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(3)
(Total 15 marks)
This question is about iron.
Iron reacts with dilute hydrochloric acid to produce iron chloride solution and one other product.
(a) Name the other product.
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(1)
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(b) Suggest how any unreacted iron can be separated from the mixture.
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(1)
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Magnesium reacts with iron chloride solution.
3 Mg + 2 FeCl3 ⟶ 2 Fe + 3 MgCl2
(c) 0.120 g of magnesium reacts with excess iron chloride solution.
Relative atomic masses (Ar): Mg = 24 Fe = 56
Calculate the mass of iron produced, in mg
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Mass of iron = ____________________________ mg
(5)
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(d) Explain which species is reduced in the reaction between magnesium and iron chloride.
3 Mg + 2 FeCl3 ⟶ 2 Fe + 3 MgCl2
Your answer should include the half equation for the reduction.
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(3)
(Total 10 marks)
Fertilisers are formulations.
(a) What is a formulation?
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(1)
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(b) A bag of fertiliser contains 14.52 kg of ammonium nitrate (NH4NO3).
Relative formula mass (Mr): NH4NO3 = 80
Calculate the number of moles of ammonium nitrate in the bag of fertiliser.
Give your answer in standard form to 2 significant figures.
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Moles of ammonium nitrate = _______________________ mol
(4)
(c) The fertiliser also contains potassium chloride.
Explain why potassium chloride has a high melting point.
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(4)
(Total 9 marks)
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Titanium is a transition metal used as pins and plates to support badly broken bones. Titanium isextracted from an ore that contains the mineral titanium oxide. This oxide is converted intotitanium chloride. Titanium chloride is heated with sodium to form titanium metal. This reactiontakes place in an atmosphere of a noble gas, such as argon.
4Na(s) + TiCl4(l) → Ti(s) + 4NaCl(s)
Calculate the mass of titanium that can be extracted from 570 kg of titanium chloride.
Relative atomic masses: Cl 35.5; Ti 48.
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Mass of titanium = ______________ kg
(Total 3 marks)
8
Petrol is a mixture of hydrocarbons such as octane, C8H18
When petrol is burned in a car engine, a large amount of carbon dioxide is produced.
9
This car uses 114 g of petrol to travel one mile.
Calculate the mass of carbon dioxide produced when this car travels one mile.
Assume that petrol is octane and that combustion is complete.
(Relative atomic masses: H = 1; C = 12; O = 16)
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The combustion of octane can be represented by this equation.
C8H18 + 12 2 → 8CO2 + 9H2O
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Mass of carbon dioxide = ____________ g
(Total 3 marks)
O
Iron is the most commonly used metal. Iron is extracted in a blast furnace from iron oxide usingcarbon monoxide.
Fe2O3 + 3CO → Fe + 3CO2
10
(a) A sample of the ore haematite contains 70% iron oxide.
Calculate the amount of iron oxide in 2000 tonnes of haematite.
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Amount of iron oxide = _____________________ tonnes
(1)
(b) Calculate the amount of iron that can be extracted from 2000 tonnes of haematite.(Relative atomic masses: O = 16; Fe = 56)
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Amount of iron = __________________________ tonnes
(4)
(Total 5 marks)
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