(1)
tabulate
Titration|Rough|1|2|3|
Final burette reading(cm3)|22.50|22.40|
22.40|22.40
initial burette reading(cm3)|0.00|0.00|
0.00|0.00
volume of acid used(cm3)|22.50|22.40|
22.40|22.40
a)
calculate the average volume of A
used=22.4 22.4 22.4/3
=22.40cm3
1b)
i)concentration of A in moldm-3
mass concentration=3.89g/dm3
molarmass=36.5g/mol
molar concentration=mass concentration/
molar mass
=3.89/36.5 moldm-3
=0.107moldm-3
1bii)
CaVa/CbVb=Na/Nb=1/1
=0.0973*22.4/Cb*25.0=1/1
Cb=0.0973*22.4/25
Cb=0.00389*22.4
=0.087136moldm-3
1biii)
molar concentration of B=40g/mol
molar concentration=0.00389moldm-3
mass concentration=molar concentration *
molar mass
=0.00389 * 22.4 *40
=3.48544g/dm3
(1c)
-To indicate the end point(copied from
(2)
Test:
A: Add 5cm3 of distilled water to all X in a
beaker.stir and filter,keep both the filtrate
and residue
B:Divide the filtrate into two portions
(i):
To the first portion add few drops of dilute
HNO3 followed by acqeous solution of
AgNO3
(ii)
:Add NH4OH in excess to the resulting
mixture on B(i)
(iii):
To the second portion add aqeous amonia
in drops.then in excess (copied from
C:Dissolve the residue in about 5cm3 of
dilute HNO3.Divide the resulting solution
into two portions
(i):To the first portion add ammonia
solution in drops
(ii):Then in excess
(iii):To the second portion add aqeous
solution of potasium iodide
(iv):Heat and allow to cool(copied from
OBSERVATION:
A:Partially soluble colourless filtrate white
residue
B(i):white precipitate
(ii)precipitate dissolved
(iii)white gelatinous precipitate.precipitate
dissolved
C:Effervescence of odourless gas which
turn lime water milky
(i):white precipitate
(ii) recipitate dissolved
(iii)yellow precipitate
(iv)dissolved on warming and reappear on
cooling(copied from
INFERENCE:
A:X contains soluble and insoluble salts
B(i):Cl- present
(ii):Cl- confirmed
(iii)Zn2 ,Al3 ,Pb2 present
Zn2 confirmed
C olourless gas is CO2 from CO3^2-
(i):Pb2 ,Al3 or Zn2 present
(ii):Pb2 ,Al3 present
(iii):Pb2 present
(iv)Pb2 confirmed
(3)
(a)i)H2S turns lead(II) acetate paper
black while SO2 does not
(copied from
(ii)Glucose-Fehlings test
-Add about 1cm3 of fehling's reagent to
about 2cm3 of the solution.Boil the
mixture
Observation:A brownish red precipitate is
observed showing the presence of
glucose
Starch-Iodide test
To an aqeous solution of the substance
add a few drops of iodide solution
Observation:solution turns blue-black
Inference:starch is present
3b)
-calcium chloride(CaCl2)
-Calcium oxide(CaO)
3c)
-Conical flask
-Burette
-Pipette
-Indicator
-Acid
-Base (copied from
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