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Tuesday 18th June
Paper II: Objective &

Essay - Chemistry 10.00
am - 1.00 pm
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Verified Chemistry OBJ:

1-10: AEECABADCB

11-20: CEADBBDEDD

21-30: DCAAADBCAB

31-40: ECAABCABAA

41-50: AADDDCCDBB

51-60: ADCCCACDCD

STILL TYPING




CHEMISTRY THORY

(1a).table
rogh-24.00,0.00 ,24.00
1-23.50,0.00,23 .502-25.50,2.00
,23.50 3-27.50,4.00,23 .50.
VA=23.50+23.50/ 3=70.50/ 3
VA=23.50 re:23.50 2nd titre:47.00
3rd titre:23.50 Volume of acid
used Rough:23.40 1st:23.50
2nd:23.503rd:23 .50 Average vol
of acid used:23.50+23.5
0+23.50/3 70.50/ 3 23.50cm^3

Equation for the reaction 2HY
(aq)+Na2Co3(aq) ---- -2NaY
(aq)+H2O(1)+CO2 (g)

(1b).CAVA/
CBVB=CA=?,CB=0. 0 5
VA=23.50,VB=25 CA*23.50/
0.05*25=2/ 1
CA*23.50*1=0.05 *25*2
=2.5/23.50 CA=2.5/ 23.5
CA=0.106moldm^3

(1ai).law of constant composition states that
samples of pure compound always contain the
same element in same mass and proportion.
(1aii).diagram for separation of petrol and water.

(1bi)the two characteristics each of physical and
chemical change are:
-physical change,no new substances is formed.
-chemical change, new substances are formed.
-Physical change much heat is not needed.
Chemical change,much heat is needed.

(1bii).physical change,seperati on of mixtures by
seperation while chemical change rusting of iron
addition of water to quicklime.

(2Ai) tabulate
observation: partially dissolve
togive colourless filtrate and black
residue Inference: C is a mixture
of soluble and insoluble salts (2bi)
Observation: whire gelationous
ppt Inference: Zn ^z+ or Al^3+
likely present

(2bii) Observation:
white gelation ppt and ppt
dissolve solube Inference: Zn ^z+
or Al^3+ likely present

(2biii)
Obersation: Insoluble in dil. Hcl
Inference: Co3^-2, So4^2- is
present

2ci) Observation: Residue
dissolved to give a pale blue
solution. Inference: Cu^2+ present

(2cii) Observation: ppt dissolves to
give deep blue solution. Inference:
Cu^2+ conformation 3 loading -

(3bii) When chlorine gas is
bubbled through potassium
bromide solution, the chlorine,
being more reactive than
bromine, displaces the bromine
from the bromide salt, in the
process, replacing the bromine
toform potassium chloride. Since
potassium chloride is soluble in
water, it remains as a colorless
solution. The displaced bromine,
however, evolves as the red-
brown liquid bromine and
bromine vapor, which would
make the solution look red/red-
brown in appearance with the
red-brown vapor floating above it.
The reaction is 2KBr (aq) +
Cl2 (g) -----> 2KCl (aq) + Br2 (l/g/
aq)


3a)

(i)electrolysis is the chemical
decompostion of compound
which takes place when an
electric current is passed
through a solution

(ii)electrode: these are
condcutors(pole s of carbon or
metal) through which an electric
current enters or leaves the
electrolyte.

(3b)
Quantity of electricity used(Q)=it
=2.6*(70*60)=84 00c
Ag(+)+2e(-)=>Ag
1 mole of AG will deposit
2*96500c=193,00 0 mass = (10*8400)/ 193,000
=4.7g


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