Candidate Name Centre Number Candidate Number 0
GCSE
ADDITIONAL SCIENCE HIGHER TIER (Grades D-A*)
CHEMISTRY 2 – Atoms, bonding and chemical change SPECIMEN PAPER
(1 hour)
INSTRUCTIONS TO CANDIDATES
Write your name, centre number and candidate number in the spaces at the top of this page.
Answer all questions.
Write your answers in the spaces provided in this booklet.
INFORMATION FOR CANDIDATES
The number of marks is given in brackets at the end of each question or part-question.
You are reminded that assessment will take into account the quality of written communication used in your answer to questions 2(a) and 8(a).
1. The graph below shows the solubility of potassium nitrate in water at different temperatures.
(i) The table below shows the solubility of potassium bromide in water at different temperatures. The solubility at 60°C is missing from the table.
Temperature
/ ºC 0 10 20 30 40 50 60 70 80
Solubility
/ g per 100g water 54 58 64 70 76 82 92 98
I Draw the graph of the solubility of potassium bromide on the grid opposite. Two points have been plotted for you. [2]
II Use the graph to give the solubility of potassium bromide at 60 °C.
[1]
……….. gper100g water
III Give the temperature at which the two compounds have the same
solubility. [1]
………. °C
IV Describe the trend in the solubility of potassium bromide and how it differs from that of potassium nitrate.
[2]
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(ii) I Emmanuel tested the solubility of a lithium compound in water at a range of temperatures from 20 to 60°C.
He was surprised to see that the solubility appeared to decrease as the temperature of the water increased.
Suggest what he should do before reporting his results to his teacher.
[1]
……….
II Give a reason why Emmanuel decided to measure and record the solubility of this compound to the nearest 0.1gper100g water. [1]
……….
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Temperature / °C
20 30 40 50 60 Solubility
/ g per 100 g water
34.8 34.2 33.7 33.2 32.6
2. (a) A chlorine atom contains 17 negatively charged electrons in orbit around its nucleus as shown in the following diagram.
Explain why a chlorine atom has no overall charge and describe the link between its electronic structure and its position in the Periodic Table.
[6 QWC]
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(b) Chlorine has two isotopes – chlorine-35 and chlorine-37.
State what is meant by the term isotopes. [1]
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3. Jan and Gareth investigated how the temperature of hydrochloric acid affected the rate of its reaction with marble chips.
They added identical amounts of marble chips to samples of acids with different temperatures and measured the time taken to collect 50 cm3 of carbon dioxide gas.
(a) Their results are shown in the following table.
Time taken to collect 50 cm3 of gas / seconds Temperature
of acid / °C
1 2 3 Mean
20 75 68 71
30 48 49 47
40 50 32 34
50 19 17 15
60 8 10 9
(i) Each experiment was performed 3 times in order to find out whether or not the results are ‘repeatable’. Identify one result from the table which should be checked e.g. by repeating the experiment once more.
[1]
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(ii) Suggest one possible explanation for this particular reading. [1]
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(iii) Calculate the mean values for the time taken to collect 50cm3 of gas at each different temperature. [2]
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(b) State the conclusion that Jan and Gareth should draw from the evidence they
have collected. [1]
……….
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(c) Another pair of students chose to investigate the effect of acid concentration on the rate of reaction.
(i) They were given acid of concentration 2.0M to be diluted to prepare solutions of lower concentrations. Suggest suitable acid
concentrations for them to use in their investigation. [2]
……….
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(ii) They found that the reaction proceeded more quickly as the
concentration increased. Explain why this is the case using particle
theory. [2]
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4. (a) A forensic scientist has recovered an ink sample from the scene of a crime and wants to compare it with samples found in the possession of three suspects.
She finds that the recovered ink has an Rf value of 0.7.
Use the information in the following chromatogram and the formula given to discover which, if any, of the inks match that from the crime scene. You must
show your working. [2]
solvent the
by travelled distance
ink the by travelled distance
value Rf =
……….
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(b) (i) Simple compounds containing potassium can be identified using a flame test.
State the flame colour seen when potassium chloride is heated in a
blue flame. [1]
………...………
(ii) Name a technique that could be used to identify and measure the amount of potassium present in biological tissue. [1]
………...………
6 5 4 3 2 1 0 cm
A B C
solvent front
5. (a) Magnesium reacts with oxygen to form magnesium oxide.
(i) Using the electronic structures given below, show by means of a diagram the electronic changes that take place during the formation of magnesium oxide. Show the charges on the ions formed. [3]
magnesium = 2,8,2 oxygen = 2,6
(ii) State why magnesium oxide is a high melting point solid. [1]
...
. ...
(b) The diagram below shows the type of bonding present in methane, CH4.
(i) Name this type of bonding. ... [1]
(ii) The bonds within the molecule are very strong. Despite this, methane has a low boiling point. State why this is the case. [1]
...
...
(c) The structures of diamond and graphite are shown below.
Give the reason why
(i) diamond is hard, [1]
...
...
(ii) graphite can be used as a lubricant. [1]
...
...
6. This question is about the halogens and the halides – the elements of Group 7 and their compounds.
(a) When bromine water is added to a solution of sodium iodide, a brown solution is formed showing that a reaction has occurred. No reaction occurs when bromine water is added to a solution of sodium chloride.
(i) Explain this difference in terms of the relative reactivities of the
halogens. [1]
...
...
(ii) Balance the following chemical equation for the reaction that takes place between bromine water and sodium iodide. [1]
Br2 + NaI → NaBr + I2
(b) Sodium bromide and sodium iodide can also be distinguished from one another by their reaction with silver nitrate solution.
Give the expected observation for one of the reactions, stating clearly to
which one it refers. [1]
...
(c) Write an ionic equation for the reaction of silver ions and chloride ions. [1]
...
7. Steve and Justin carried out an investigation to find the relative hardness of four water samples, A, B, C and D. They added soap solution to each sample, shook the mixtures and recorded the time taken for the lather to disappear.
Their results are as follows.
Time for lather to disappear / s
Test 1 Test 2
A 310 300
B 400 410
C 30 30
D 90 100
(i) Giving a reason for your answer, state which water sample is the hardest.
[1]
……….
(ii) Three other groups carried out similar investigations and they recorded their results in the same table.
Time for lather to disappear / s Group 1 Group 2 Group 3
A 180 250 80
B 220 400 100
C 20 40 10
D 80 100 20
State to what extent these results confirm your conclusion in (i).
Suggest a possible reason for the difference between each group’s results.
[2]
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(iii) State which ions, in addition to calcium ions, cause hardness in water. [1]
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8. (a) Explain how crude oil is separated into different fractions. [6 QWC]
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(b) When ethene, C2H4, burns in air, carbon dioxide and water are formed as shown in the following equation.
C2H4 + 3O2 2CO2 + 2H2O
The relative amounts of energy needed to break the bonds in the reactants are shown in the table below.
Bond Amount of energy needed to break bond / kJ
C = C 612
C – H 413
O = O 496
(i) Use these values to calculate the relative energy (in kJ) needed to break all the bonds in the reactants. [2]
……….
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(ii) 4828kJ of energy are released when new bonds are formed in the products. Calculate the overall energy change for the reaction.
[1]
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9. (a) Smart materials have unusual properties. Describe the unusual property that (i) smart alloys show on heating, [1]
...
(ii) thermochromic materials show on heating. [1]
...
(b) The most effective and widely used smart alloy is nitinol which contains 50% titanium.
Titanium, Ti, is a metal which is extracted from ores containing titanium(IV) oxide. This oxide is converted into titanium(IV) chloride, TiCI4, which is then reacted with either sodium or magnesium to form titanium metal. The equation below shows the formation of titanium from titanium chloride using sodium.
TiCI4 + 4Na Ti + 4NaCI
Ar(Na) = 23 Ar(Ti) = 48
(i) Use the equation above to calculate how many tonnes of sodium would be needed to produce 96 tonnes of titanium. [3]
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...
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(ii) Titanium forms another chloride in which 48g of titanium is combined with 71g of chlorine. Calculate the simplest formula for this chloride of
titanium. Show your working. [2]
Ar(CI) = 35.5 Ar(Ti) = 48
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FORMULAE FOR SOME COMMON IONS
POSITIVE IONS NEGATIVE IONS
NAME FORMULA NAME FORMULA
Aluminium Al3+ Bromide Br-
Ammonium NH4+ Carbonate CO32-
Barium Ba2+ Chloride CI-
Calcium Ca2+ Fluoride F-
Copper(II) Cu2+ Hydroxide OH-
Hydrogen H+ Iodide I-
Iron(II) Fe2+ Nitrate NO3-
Iron(III) Fe3+ Oxide O2-
Lithium Li+ Sulfate SO42-
Magnesium Mg2+
Nickel Ni2+
Potassium K+
Silver Ag+
Sodium Na+
