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ST. JOSEPHS’ BOYS HIGH SCHOOL
CAT 1 TERM 2 2008
CHEMISTRY
FORM 3
TIME: 2 HOURS
NAME...........................................................................ADM NO.......................CLASS...............
TOTAL MARKS - 80
1. Carbon dioxide can be dissolved in water under pressure to make an acidic solution.
a) What is meant by an acidic solution.
( 1 Mark )
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b) Aqueous Lead (II) nitrate reacts with the acidic solution to form a precipitate. Write
an ionic equation for the reaction.
( 1 Mark )
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2. When 94.5g of hydrated barium hydroxide Ba CO H)2 . H2O were heated to constant
mass, 51.3g of anhydrous barium hydroxide were obtained. Determine the Empirical
Formula of the hydrated barium hydroxide.
( Ba = 137.0, O = 16.0, H = 1.0 )
( 3 Marks )
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3. a) Starting from solid magnesium oxide, describe how a solid sample of magnesium
sulphate can be prepared.
( 2 Marks )
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b) Give one use of magnesium hydroxide.
( 1 Mark )
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4. Distinguish between a covalent bond and a co-ordinate bond.
( 2 Marks )
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5. The simplified diagram below shows some of the steps in the manufacture of sodium
carbonate by solvay process.
L
CO2
BRINE
Step I
Ammonia chloride
and sodium hydrogen
carbonate
Step II
Sodium hydrogen
Carbonate
Ammonium
chloride
Step III
Sodium carbonate
a) Identify substance L.
L
( 1 Mark )
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b) Name the process taking place in step II.
( 1 Mark )
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c) Write an equation for the reaction taking place in step III.
( 1 Mark )
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d) i) Name the waste by-product in the solvay process.
( 1 Mark )
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ii) State two uses of the above waste product.
( 2 Marks )
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e) State three commercial uses of sodium carbonate.
( 3 Marks )
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6. A gas occupies 36 cm3 and 750 mmHg pressure at 25ºC. At what temperature will the
same mass of gas occupy 72 cm 3 at 1000 mmHg pressure.
( 3 Marks )
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7. The diagram below represents an incomplete set up of apparatus that can be used to
prepare and collect dry carbon(iv) oxide gas. Complete the diagram and answer the
questions that follow.
( 2 Marks )
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a)
i) Write an equation for the reaction which takes place.
( 1 Mark )
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ii) Name liquid Z.
( 1 Mark )
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iii) Why would it not be suitable to use Lead Carbonate in place of Calcium
Carbonate in this set-up.
( 2 Marks )
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b) When a piece of burning magnesium is lowered unto a gas jar full of carbon(iv) oxide
it continues to burn to form a whit e solid and black specks.
i) Name the white solid and black specks.
( 2 Marks )
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8. A weighed sample of crystalline sodium carbonate Na2 CO3 and H2O, was heated in a
crucible until there was no further change in mass. The mass of the sample reduced by
145%. Calculate the number of moles (n) of the water of crystallization ( Na = 23, O=16,
C = 12 H = 1 )
( 3 Marks )
9. On complete combustion, 0.09 moles of a hydrocarbon T produced 19.8 g of carbon
dioxide and 9.72 of water ( C=12, H = 1, O= 16 )
a) Determine the Empirical Formula of a compound T.
( 2 Marks )
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b) Determine the molar mass of T.
( 1 Mark )
c) Determine the molecular Formula of the compound T.
( 1 Mark )
10. When 1.3 g of metal L were added to an excess solution of the nitrate metal M ( M NO 3 ).
432 g of metal M were displaced ( L = 65, M = 108 )
a) i) L
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( 1 Mark )
ii) M
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( 1 Mark )
b) Write an ionic equation for the reaction that takes place.
( 1 Mark )
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11. The electron arrangements of the ions Q+ and P2 are 2.8.1 and 2.8.7 respectively. Identify
the element Q and P from the periodic table.
( 2 Marks )
Q
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P
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12. A given volume of methane (CH4) diffuses from a certain apparatus in 96 seconds. The
same volume of a gas x diffuses from the same apparatus under similar conditions in 88
seconds. Calculate the relative molecular mass of gas x ( C = 12, H = 1 ) ( 3 Marks )
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13. Dry ice is more suitable for use in Refrigerators than normal ice. Explain.
( 2 Marks )
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14. Use the table below to answer the questions that follow. ( the letters are not the actual
symbols of the elements )
Element
A
B
C
D
E
Atomic
Number
11
13
14
17
19
Mp ( ºC )
97.8
660.0
1410.0
-101.0
03.7
a) Write the electronic arrangement for the ions formed by the elements B and D.
B
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D
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b) Select an element which is :i) A poor conductor of electricity.
( 1 Mark )
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ii) The most reactive non-metal.
( 1 Mark )
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c) To which period of the periodic table does element E belong.
( 1 Mark )
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d) Element E loses its outermost electron readily than A. Explain .
( 2 Marks )
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e) Use dots ( . ) and crosses ( x ) to represent the outermost electrons, and show the
bonding in the compound formed between elements C and D.
( 2 Marks )
f) Explain why the melting point in element B is higher than that of element A.
( 2 Marks )
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g) Write an equation for the reaction that takes place between element A and water.
( 2 Marks )
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15. Justify the use of the following apparatus in the laboratory in relation to their shapes.
a. Flat bottomed flask.
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b. Round bottomed flask.
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16. A student added dilute sulphuric (vi) acid to an alkaline solution of potassium
Hydroxide drop wise in a flask.
a. How will the student determine that all the alkaline in the flask has reacted.
( 1 Mark )
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b. Write an equation to show the reaction above.
( 1 Mark )
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c. When the product is evaporated to dryness name the solid residue in the flask.
( 1 Mark )
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17. Study the diagram below and answer the questions that follow.
a) Explain why the gas is collected using the above method.
( 2 Marks )
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b) i) What is the purpose of solution X.
( 1 Mark )
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ii) Name solution S.
( 1 Mark )
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c) Write a chemical equation for the reaction taking place in the round bottomed flask.
( 2 Marks )
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d) Explain the following statements.
i) Copper does not react with dilute acids.
( 1 Mark )
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ii) Zinc is preferred in preparing hydrogen than magnesium and Aluminium.
( 2 Marks )
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18. Magnesium turnings were heated in a crucible whose lid was periodically lifted until
there was no observable change.
i) State the observations made whenever the lid was lifted during the early stages of the
experiment.
( 2 Marks )
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ii) What was the purpose of periodic lifting and replacement of the id? Give two
reasons.
( 2 Marks )
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iii) Write a chemical equation for the reaction taking place.
( 1 Mark )
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iv) A sample of the product was put in a boiling tube and distilled water added an the
mixture shaken thoroughly. Which type of solution was formed? Which test would
show this?
( 2 Marks )
Type of solution
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Test of show.
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END