NAME: ____________________________
Chemistry 2012
YEAR 11
HALF-YEARLY EXAM
GENERAL INSTRUCTIONS
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This exam is based on the topic ‘The Chemical Earth’ and the first section of ‘Metals’.
Attempt ALL questions
Working time – 1 hour (no separate reading time)
Write your name on your question and answer papers.
You will require a calculator for this exam.
Write all answers in the spaces provided in the answer booklet using a blue or black pen.
Draw diagrams using pencil.
Anything written in the question book will not be marked.
If you require scrap paper for working ask your supervising teacher.
A copy of the Periodic Table of the Elements and Data Sheet is supplied.
Total Marks = 50
PART A MULTIPLE CHOICE (15 marks)
Select the alternative A, B, C or D that best answers the question.
Place a cross in the correct space on your answer sheet.
1. A white powder was heated until it decomposed at 500 °C.
A temperature – time graph of the initial heating process
is shown at right.
Based on the information provided, the white powder was
probably
Temperature °C
250
200
150
100
(A) a mixture of elements
(B) a mixture of elements and compounds
(C) an element
(D) a compound
50
0
Time of heating (minutes)
2. The formula of sodium nitrate is NaNO3. The correct formula for iron (III) nitrate is
(A) Fe3(NO3)2
(B) Fe(NO3)3
(C) Fe2(NO3)
3. The cation with electron configuration 2.8.8 is
(A) the potassium ion
(C) the sodium ion
(B) the chloride ion
(D) argon
(D) Fe3NO3
4. Oil and water are immiscible, they do not dissolve in each other. The best way of separating
this mixture in the laboratory is by
(A) filtration
(C) a chromatography column
(B) use of a centrifuge.
(D) use of a separating funnel
5. Which of the following elements is present in living things in greatest proportion by mass?
(A) Oxygen
(C) Nitrogen
(B) Carbon
(D) Hydrogen
6. Which of the following is NOT a chemical property of magnesium?
(A) Magnesium burns in air to form magnesium oxide.
(B) Magnesium conducts electricity in the solid and molten states.
(C) Magnesium reacts with acids to produce hydrogen gas.
(D) Magnesium is more active than zinc.
7. Which of the following elements is classified as a semi-metal (metalloid)?
(A) Iodine
(B) Sulfur
(C) Silicon
(D) Zinc
8. The substance which would conduct electricity in the molten state but not in the solid state is
(A) potassium chloride
(C) lithium
(B) iodine
(D) carbon dioxide
9. An element which exists as a diatomic molecule at room temperature is
(A) chlorine
(B) carbon
(C) neon
(D) lithium
10. Which of the following lists only pure substances?
(A) Ice, air, chlorine, sodium
(B) Steel, copper (II) chloride, hydrogen, iron
(C) Diamond, magnesium, water, sodium chloride
(D) Carbon, sodium, brass, nitrogen
11. The most likely formula for the compound formed between strontium and fluorine is
(A) SrF
(B) SrF2
(C) Sr2F2
(D) Sr2F
12. Which of the following atoms is MOST likely to form positive ions with a charge of +2?
(A) O
(B) Na
(C) Ba
(D) Cl
13. Which of the following shows the atomic structure of an isotope of magnesium?
(A)
(B)
(C)
(D)
protons
24
24
12
12
electrons
24
24
13
12
neutrons
24
25
12
13
14. Which of the following elements is LEAST likely to be involved in chemical reactions?
(A) Ca
(B) Cu
(C) Sn
(D) Au
15. Four gas samples were analysed. Each was found to be a compound of carbon and hydrogen only.
The composition of each gas is shown in the table below.
Sample
No.
1
2
3
4
Mass of Carbon
Present (g)
12.0
24.0
18.0
6.0
Mass of Hydrogen
Present (g)
4.0
6.0
4.0
2.0
From this data, which two samples do you conclude are most likely to be the same gas?
(A) 1 and 4
(B) 1 and 3
(C) 2 and 3
(D) 2 and 4
PART B SHORT ANSWER QUESTIONS (35 marks)
Allow about 45 minutes for this part.
Write your answers in the spaces provided on your answer sheet.
Question 16 (8 marks)
A laboratory assistant tripped and dropped a tray containing four previously weighed chemicals so that
they all mixed together. The four chemicals are listed below.
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tin pieces (6.2 g)
graphite powder (4.9 g)
alcohol (12.8 g)
solid wax (5.9 g)
The wax dissolved in the alcohol.
(a) Show, using a flow diagram, how the laboratory assistant could separate and get back each of the
four chemicals from the mixture.
(b) Identify a different property of two of the substances shown above for two separation processes
you used.
(c) Calculate the percentage by weight of wax in this mixture?
Question 17 (2 marks)
Name one common mixture that is separated industrially and identify one important process used
in this separation.
Question 18 (4 marks)
Draw Lewis electron-dot diagrams to represent:
(a) an atom of oxygen
(b) a molecule of ammonia (NH3)
(c) a fluoride ion
(d) a sodium ion
Question 19 (2 marks)
When magnesium metal is burned in the presence of chlorine gas, the salt magnesium chloride is formed.
(a) Write the formula of magnesium chloride.
(b) Write an ionic equation that represents magnesium atoms forming ions.
Question 20 (8 marks)
Models representing four solids (P, Q, R and S) are shown below.
Model 1
Model 2
Model 3
Model 4
Some properties of these four solids are summarised in the following table.
Solid
P
Q
R
S
Melting
point
(°C)
800
358
3500
44
Relative
conductivity
of solid
0
8
0
0
Relative conductivity
of the liquid formed
by melting the solid
3
5
0
0
Effect of
hammering
the solid
forms a powder
flattens
shatters
forms a powder
(a) Use the properties of the solids P, Q, R and S to match them with the Models 1, 2, 3 and 4.
(b) Explain in terms of structure and bonding:
(i) the difference in conductivity of solids P and Q.
(ii) why solids R and S have such different melting points.
(iii) why solid Q flattens when hammered.
(c) Choose one of the models shown and outline one clear limitation that it presents.
Question 21 (4 marks)
The diagram on your answer sheet shows drawings of four water molecules. Complete the diagrams
to show what happens when all four water molecules are heated to water’s boiling point and when all four
water molecules are electrolysed.
Question 22 (4 marks)
(a) Define the term ‘alloy’.
(b) (i) Name one commonly used alloy.
(ii) State a common use of this alloy and relate one property of the alloy to this use.
(c) Suggest one clear reason why there is a greater variety of metals used by people today than there
was 200 years ago.
Question 23 (3 marks)
Write balanced equations for the following:
(a) Magnesium reacts with a dilute solution of sulfuric acid (H2SO4).
(b) Potassium reacts with oxygen.
(c) Calcium reacts with water.
End of Test