Gay Lussac’s of combining volumes states that gases react in simple ratio with one another and to volumes of the products provided that temperature and pressure remain constant. In this article, you will understand how to apply this law in calculation by studying the following examples below: 1. 2H 2 + O 2 → H 2 O In the reaction above, what volume of hydrogen would be left over when 300cm 3 of oxygen and hydrogen are exploded in a sealed tube? 1cm 3 of oxygen = 2cm 3 of hydrogen 300cm 3 of oxygen = 2 x 300 = 600cm 3 Volume of left over = 1000 – 600 = 400cm 3 2. Calculate the volume of carbon (II) oxide required to react with 40cm 3 of oxygen. 2CO + O 2 → 2CO 2 1cm 3 of oxygen = 2cm 3 of CO 40cm 3 of oxygen = 2 x 40 = 80cm 3 3. Calculate the volume of residual gases that would be produced when 100cm 3 of sulphur (IV) oxide reacts with 20cm 3 of oxygen 2SO 2 + O 2 → 2SO 3 1cm 3 of O 2 = 2cm 3 20cm 3 of O 2 = 2 x 20 = 40cm 3
CHEMISTRY SPECIMEN
In addition to the fitting
and reagents normally found in a chemistry laboratory, the following apparatus
and materials will be required by each candidate:
a)
One burette of 50cm3 capacity
b)
One pipette either 20cm3 or 25cm3
( All candidates at one centre must use pipette of the same volume. These should
be clean and free from grease)
c)
The usual apparatus for titration
d)
The usual apparatus and reagents for qualitative
work including the following with all reagents appropriately labelled
I.
Dilute sodium hydroxide solution
II.
Dilute hydrochloric acid
III.
Dilute trioxonitratrate (V) acid
IV.
Silver trioxonitrate (V) solution
V.
Acidified potassium dichromate solution
VI.
Aqueous ammonia
VII.
Lime water
VIII.
Red and blue litmus paper
IX.
Dilute tetraoxosulphate (VI) acid
X.
Fehling’s solution A and B
e)
Spatula
f)
Filtration apparatus
g)
One beaker
h)
One boiling tube
i)
Four test tubes
j)
Methyl orange as an indicator
k)
Glass rod
l)
Wash bottle
m)
Burning splint
n)
Watch glass
o)
Bunsen burner/source of heat
p)
Droppers
q)
Mathematical table/calculator
1.
Each candidate should be supplied with the following: where “n” is the candidate’s serial
number.
2.
150cm3 of a solution of HCl in a
corked flask or bottle labelled “An”.
These should all be the same containing 8.5cm3 of concentrated HCl
per dm3 of solution.
3.
150cm3of Na2CO3.10H2O
in a corked flask or bottle labelled “Bn”.
The same containing 5.0g of the hydrated salt per dm3 of solution.
4.
One spatulaful of glucose in a specimen bottle labelled
“Cn”. This must be the same
for all candidates.
5.
One spatulaful of zinc oxide powder in a
specimen bottle labelled “Dn”.
This must be the same for all candidates.
BIOLOGY SPECIMEN
A.
= matured fresh eggs of catfish
B.
= fresh egg of domestic fowl
C.
= picture/model of uterus containing foetus
D.
= longitudinal section of ovary
E.
= leaf of pride of Barbados
F.
= Panicum plant/ guinea grass whole plant
G.
= Cocoyam plant
H.
= Corm of cocoyam
I.
= Dry humus in a beaker
J.
= dry humus in a beaker
K.
= Moist humus in a beaker
L.
= Ripe orange fruit
M.
= longitudinal section of coconut fruit
N.
= longitudinal section of fresh chilli pepper
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