Chemistry/Additional Science
Unit C2: Discovering Chemistry
Grade 1
Time: 60 minutes
Name of the Candidate ...................................................
Ionic compounds
1. Sodium carbonate and copper chloride are both ionic solids.They are both soluble in water.
(I)
(a) Which row of the table shows the most likely melting points of these two salts?
melting point I C
sodium carbonate copper chiord•
17
498
851
9
tC C3
851
498
Dfl
9
17
A
(b)Complete the sentence by putting a cross( X) in the box next to your answer.
If a flame test is carried out on copper chloride, the colour in the flame is
(1)
LIII A red-brown
LI B yellow
LII C lilac
LI
D green-blue
(c)Copper carbonate is an insoluble salt.Describe how you would use sodium carbonate and copper chloride
(3)
to produce a pure, dry sample of copper carbonate.
*(d) Explain the difference in the ability of solid sodium chloride and molten sodium chloride to conduct
(6)
electricity in terms of their structures.
(Total for Question I = ilmarks)
Group 1
2.Lithium, sodium and potassium all react with cold water.
(a) Lithium, sodium and potassium are in group I of the periodic table.
(1)
Complete the sentence by putting a cross ( X) in the box next to your answer.
These elements are
LI A halogens
LI
B noble gases
ED C transition metals
0 D alkali metals
(b) When sodium is added to cold water, it forms a molten ball which floats on the surface of the water.
(2)
Explain why this happens.
Page 1 of 4
(c)The reaction of sodium to form sodium oxide can be described as oxidation because
it involves the addition of oxygen.
(1)
State one other reason why this reaction can be described as oxidation
(2)
(d)Explain why water has a much lower melting point than sodium oxide.
The diagrams show the electron arrangement in an atom of sodium. Draw the arrangement of electrons in
(1)
sodium ion.
(e) A teacher added sodium oxide to water in a beaker.
The equation shows the reaction that occurred.
Na20(........) + HO(........) -p 2NaOH(........)
(i) Insert the appropriate state symbols in this equation.
(2)
(ii) Some universal indicator was then added to the beaker. A colour change occurred.
State the final colour of the universal indicator and identify the ion responsible for the colour change. (2)
(Total for Question 6 = 11 marks)
Group 7
3. This question is about bromine and some of its comounds.
(a) Atoms of bromine can be represented as 79Br and 8 Br
(i) State the number of protons, neutrons and electrons in an atom of 79Br35
(2)
(ii) What name is used for atoms of bromine that have different numbers of neutrons?
(I)
(iii) The relative atomic mass of bromine is given in the Periodic Table as 80, but amore accurate value is
79.9. Suggest, with a reason, which of the atoms 7913r and 81Br exists in greater numbers in a sample of
bromine.
(2)
(Total for Question 6 = 5 marks)
Quantitative Chemistry
4.(a) A compound has the percentage composition 13.8% sodium, 47.9% bromine and 38.3% oxygen by
mass. Calculate its empirical formula.
(3)
(b)Fertilisers are used to promote plant growth.
The equation for the production of ammonia is
2NH3
N2(g) + 31-12(g)
>
Calculate the maximum mass of ammonia that can be obtained from 56 tonnes of nitrogen.
(3)
(I tonne = 1 000 000 grams)
(Total for Question 4 = 6 marks)
Hydrocarbons
5.The alkenes are a series of unsaturated hydrocarbons. They have the general molecular formula CH2 .
(a) Deduce the molecular formula of an alkene which has a relative molecular mass of 126. Show your
working.
(2)
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(b) The structural formula of propene is drawn below.
H H H
I I
H
H
(I) Draw a dot and cross diagram showing the arrangement of the valency electrons in one molecule of this
covalent compound.
(3)
Use x to represent an electron from an atom of carbon. Use o to represent an electron from an atom of
hydrogen.
(Total for Question 5 = 5marks)
Rate of reactions
7.A student carried out an experiment to investigate the speed of reaction between 50 cm of dilute
hydrochloric acid and excess zinc powder using the apparatus shown below.
The reaction was carried out at a room temperature of 25 °C.
a) The volume of gas produced was measured every minute for six minutes. Use the syringe diagrams to
complete the table of results.
(3)
Wnelmirrutes
o
vo urre of gas collacted /crri
gas syringe diag ram
=fiIiIIli.
ii
IIl
11111
Ii
U IlIIIP!
111111 qu,
I
lilT
10
50
111 II TI 1111151 IlIIIHI u
u
IuulIl1lINhulIlTTIlIITI
_l
ITTT
*
0
00
I.
Ill
20
10
40
30
.............
ITIll1..n..9
50
4)
UT]9.nTTT.
TI"T"l
so
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.
5
__b
II
6
10
tIll 11111 U
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20
36
4
o...
tl Ill 1111 11111111111 III 111111
40
30
20 30
IUT
00
(b)Plot the results on the grid and draw a smooth line graph
(3)
(ii) At which time does the result appear to be inaccurate?
(iii) Use your graph to work out the volume of gas that should have been recorded at
this time. Show clearly on the grid how you obtained your answer.
(c) Sketch, on the grid, the graph you would expect if the experiment was repeated at 50 °C
(Total for Question 7 = 10 marks)
(1)
(2)
(1)
Carbon
8. Diamond and graphite are two naturally-occurring forms of carbon.
The diagrams below show the arrangement of the carbon atoms in diamond and in graphite. The black dots
(.) represent carbon atoms.
Page 3 of 4
(a) Name the type of structure in diamond and explain, in terms of its bonding, why diamond has a high
melting point.
(4)
(b)The structure of graphite has one feature in common with that of metals. This feature allows graphite to
conduct electricity.
Suggest what this feature is and why it allows graphite to conduct electricity.
(2)
(Total for Question 8 = 6 marks)
Chromatography
9. Paper chromatography can be used to separate a mixture of food dyes (M), and identify which dyes are
present. The diagram shows the apparatus used.
.,1.*.,b .I
fod dyr.
(a) The food dyes are placed on the paper about 2 cm up from the bottom edge. Why is
it important not to place them at the bottom of the paper?
(b) State two observations you would make during the experiment.
(c)At the end of the experiment the paper is removed and dried. The diagram shows thepaper.
(1)
(2)
(i) Measure the distance moved, in centimetres, by food dye R during the experiment.
(1)
(ii) Which of the food dyes P, Q. R and S are present in M?
(1)
(iii) Food dyes P and S did not move very far. Suggest one change you could make to this experiment to help
them move further.
(1)
(Total for Question 9 = 6 marks)
Total Marks for the paper: 60
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