2012 Waec examination Expo: Waec examination CHEMISTRY SPECIMENS- Biology Questions and Answers.
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(1)burette of 50cm
pipette, either 20cm
or 25 (using d
usual apparatus for
(i)red and blue litmus
trioxonitrate (V) acid
A. 150cm of
solution in a corked
H2SO4 (about 98%
w/w)per dm of
B. 150cm of NaOH
solution, in a
corked flask or bottle
containing 3.9g of
NaOH per dm of
C. 10cm of
(NH4)2SO4 solution in
bottle labelled ‘C’
containing 66g of
(NH4)2SO4 per dm of
D. 10cm of FeCl3
solution in a bottle
labelled D containing
40g of FeCl3
per dm of solution.
2012 REAL AND CONFIRMED WAEC
CHEMISTRY PRACTICAL QUESTION
Question 2a (salt analysis)=>
c&d are acqeous solution of two
simple salts. carry out the fll
exercises on c&d, record your
observations identify any gas
evolved. State the conclusion you
draw from the result of each test. A.
Divide solution c into four portions. 1.
1st portion of c= add NaOH solution in
drops and then in excess.
(ii). 2nd portion of solution c = add
acqeous amonia in drops and then in
excess. (iii). 3rd portion of c= add
NaOH solution and warm. (iv). 4th
portion of c= add barium chloride
solution followed by dilute
hydrochloric acid in excess
2b. divide solution d into five
portions.i. to the first portin add NaOH
in drops then in excess ii. to the
second portion add acqeous amonia
in droos then in excessiii. to the third
portion add dilute trioxonitrate (v)
acid followed by silver trioxonitrate
(v) solutioniv. to the fourth portion
add silver trioxonitrate (v) solutionv.
add few drops of solution D into
solution C and warm.
2012 CHEMISTRY ANALYSIS 1
1a)Small portn of sample C+NaOH
b)Anoda portn of sample C+BaCl
2a)Small portn of spec.D+NaOHaq
drop den in
b)Small portn of sample D+NH3aq
drop den in
3a)Small portn of sample D+dil.HNO3
b)Soln formed above+NH3aq drop
den in excees.
1a)A colourless gas with pungent
smell dat turn
moist litmus paper blue.
b)White ppt is formed which is
insoluble in dil.HCL.
2a)Redish brown ppt is formed which
is insoluble in
b)Brown ppt which is insoluble in
3a)White ppt is formed.
b)White ppt dissolve to form a clear
1a)NH3g 4rm NH4+ salt.
b)SO4 raise to power 2- is
2a)Fe^3+ is comfirmed.
b)Fe^3+ is comfired.
3a)Cl^- is present.
b)Cl^- is present.
> VOLUMENTRIC ANALYSIS Na2X + 2H2O.
Burrete reading (cm3)
Rough | 1st | 2nd | 3rd
28.50 | 26.40 | 25.60 | 26.50
1.00 | 2.00 | 1.00 | 2.00
27.50 |24.40 |24.60 | 24.50
(N.B folow d order i.e final reading,
initial reading and volume of A used).
Average Volume of Acid used =
= (73.50/3) =24.50cm3.
2.45g ==> 500cm3
:. x= (2.45 *100)/500
i.) Cb = mas concentration/molar
ii.) CaVa/CbVb =na/nb ; Va
Vb=25cm3, na=1, nb=2.
iii.) Ca = mass concentration / molar
molar mass =4.90/0.0497
(1*2) + X =98.6
X= 98.6 -2
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