Download Practical Chemistry

CPC – 1
PRINCIPLES RELATED TO
PRACTICAL CHEMISTRY
Syllabus :
Detection of extra elements (N, S halogens) in
organic compounds; Detection of the
following functional groups; hydroxyl
(alcoholic and phenolic), carbonyl (aldehyde
and ketone), carboxyl and amino group
in organic compounds
Chemical involved in the preparation of the
following :
Inorganic compounds; Mohr’s salt, potash
alum.
Organic
compound
: Acetanilide,
p-nitroacetanilide, aniline yellow,
iodoform
Chemistry involved in the titrimetric excercises
- Acids bases and the use of indicators, oxalicacids vs KMnO4, Mohr’s salt vs KMnO4.
Cations - Pb2+, Cu2+, AI3+, Fe3+, Zn2+, Ni2+, Ca2+,
Ba2+, Mg2+, NH4+
Anions - CO32–, S2–, SO42–, NO3–, CI–, Br, I (Insoluble salts excluded)
Chemical principles involved in the following
experiments :
Einstein Classes,
1.
Enthalpy of solution of CuSO4
2.
Enthalpy of neutralization of strong acid and
strong base.
3.
Preparation of lyophilic and lyophobic sols.
4.
Kinetic study of reaction, of iodide ion with
hydrogen peroxide at room temperature
Unit No. 102, 103, Vardhman Ring Road Plaza, Vikas Puri Extn., Outer Ring Road
New Delhi – 110 018, Ph. : 9312629035, 8527112111
CPC – 2
E X E R C I S E (OBJECTIVE)
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
(a)
Al(OH)3Zn(OH)2
We have aq. solution of Zn(CH3COO)2 and ZnCl2
in test tubes I and II (separate). H2S gas is passed
into each, then ZnS is precipitated :
(b)
AlCl3, ZnCl2
(a)
In I
(b)
In II
(c)
Fe(OH)3, Mg(OH)2
(c)
in both
(d)
in none
(d)
Fe(OH)3, Al(OH)3
Excess of NaOH added will separate :
11.
12.
NaOH can be used to separate :
(a)
CuS, As2S3
(b)
Al(OH)3, Cr(OH)3
(c)
both
(d)
none
Acidified K2Cr2O7 changes to green on reaction with
13.
On heating colourless solid A, gas B (liquid at room
temperature) and gas C are formed. A is
decomposed by NaOH on heating to form gas D
giving white fumes with HCl. Gas C occupies 800
ml/g at N.T.P. Hence A is
(a)
NH4NO3
(b)
NaNO2
(c)
NH4Cl
(d)
NH4NO2
Na 2 S gives purple colour with sodium
nitroprusside. Purple colour has formula
(a)
SO2
(b)
FeSO4
(a)
Na3[Fe(CN)6S]
(c)
KI and then adding hypo
(b)
Na2[Fe(CN)5NOS]
(d)
All of these
(c)
Na4[Fe(CN)5NOS]
(d)
KFe[Fe(CN)5NOS]
On adding Fe 2+ to [Fe(CN) 6] 3—, blue colour is
formed. This is called
(a)
Prussion blue
(b)
Turnbull’s blue
(c)
Blue chrome T
(d)
none
14.
15.
This reagent is/are used to separate IIA
(copper group) from IIB (arsenic group) :
(a)
YAS
(b)
(c)
H2S + HCl
(d)
NaOH
16.
both (a) and (b)
Fe2+
(b)
C2O42—
(c)
both
(d)
none
(a)
CH3COOH
(b)
CH3COONH4
(c)
both
(d)
none
As2S3 is soluble in (NH4)2S2 forming
(a)
(NH4)3AsS4
(b)
(NH4)2AsS3
(c)
(NH4)3AsS3
(d)
none is true
Following gives yellow ppt on boiling with conc.
HNO3 and ammonium molybdate
AsO43—
(a)
KMnO4 is decolorised on reaction of a mixture in
acidic medium. Mixture contains
(a)
PbSO4 is soluble in
(c)
17.
NO
PO4
—
3
3—
FeSO4.HNO2
Gas (X) turns lime water milky. It can be
(b)
[Fe(H2O)5NO]2+
(a)
CO2
(b)
SO2
(c)
FeSO4.NO2
(c)
both
(d)
none
(d)
Fe(OH)2.NO
18.
(a)
CrO+
(b)
CrO22+
(c)
CrO2+
(d)
CrO23+
CaC2O4 is soluble in
(a)
HCl
(b)
H2SO4
(c)
CH3COOH
(d)
all
This reagent gives ppt with KI followed by hypo
addition
(a)
CuSO4
(b)
HgCl2
(c)
FeCl3
(d)
a, b true
Einstein Classes,
19.
20.
Pb2+
(d)
both (a) and (c)
is detected by ring test. Ring has formula :
(a)
Chromyl ion is
(b)
There is formation of blue colour when (KI + starch)
is added to
(a)
HNO2
(b)
CuSO4
(c)
Cl2
(d)
all of these
FeCl3 forms blood red colour with KCNS. Blood
red colour is due to
(a)
Fe(CNS)3
(b)
[Fe(CNS)]2+
(c)
[Fe(CNS)2]+
(d)
none is true
Which give(s) yellow ppt with K2CrO4 :
(a)
Ba2+
(b)
Pb2+
(c)
Cu2+
(d)
both (a) and (b)
Unit No. 102, 103, Vardhman Ring Road Plaza, Vikas Puri Extn., Outer Ring Road
New Delhi – 110 018, Ph. : 9312629035, 8527112111
CPC – 3
21.
22.
23.
24.
25.
26.
27.
28.
29.
30.

Black residue (MnO2) + K2CO3 + air 
 (green)
X + Cl2  Y (pink). X and Y are :
(a)
K2Cr2O7, KMnO4
(b)
K2MnO4, KMnO4
(c)
(d)
KMnO4, K2MnO4
none
31.
32.
Removal of PO43— (interferring radical) is necessary :
33.
(a)
after group III
(b)
after group II but before III
(c)
after group II
(d)
no necessity
Borate forms green edged flame when burned with
conc. H2SO4 + ethanol. Green edged flame has
formula.
34.
2—
3—
6
Amongst TiF6 , CoF , Cu2Cl2 and NiCl42— the
colourless species is/are :
(a)
Cu2Cl2
(b)
TiF62—
(c)
NiCl42—
(d)
both (a) & (b)
Which one of the following pairs of ions can be
separated by H2S in dilute HCl acid
(a)
Ni2+, Cu2+
(b)
Al3+, Hg2+
(c)
Zn2+, Cu2+
(d)
all of these
Which of the following anions is not easily removed
by precipitation from its aqueous solution ?
(a)
NO3—
(c)
SO42—
(b)
(d)
2+
Hg2+, Pb2+
(a)
(C2H5O)3B
(b)
(C2H5)2BO2
(b)
Pb2+, Cu2+, Ag+
(c)
(C2H5)3BO3
(d)
both (a) & (c)
(c)
Pb2+, Ag+
(d)
Hg2+, Pb2+, Cu2+, Ag+
When KNO2 is added to Co2+ salt in acetic acid
medium, yellow ppt is formed. It is due to
(a)
K4[Co(NO2)6]
(b)
(c)
KCo[Co(NO2)6] (d)
35.
K3[Co(NO2)6]
none
CrO42— (yellow) changes to Cr2O72— (orange) at pH
= x and vice versa at pH = y. x and y can be
(a)
6, 5
(b)
6, 8
(c)
8, 9
(d)
7, 7
Green Cr3+ changes to yellow CrO42— on boiling with
(a)
alkaline H2O2
(b)
acidified H2O2
(c)
both
(d)
none
36.
Ammonium dichromate is used in some fireworks.
The green coloured powder blown in the air is
(a)
CrO3
(b)
Cr2O3
(c)
Cr
(d)
CrO(O2)
2+
A substance “A”, which sublimes on heating,
evolves a colourless gas when treated with HCl and
a small quantity of NaNO 2. Suggest from this
information a suitable test for A :
(a)
Nessler’s test
(b)
brown ring test
(c)
decolorization with acidified KMnO4
(d)
lime water test
Black HgS :
(a)
dissolves on boiling with conc. HCl
(b)
does not dissolve in boiling HCl + a
crystal of KClO3
(c)
dissolves in NaOH solution
(d)
none is correct
(a)
An aq. solution of NH4Cl is acidic
A chloride in acid solution decolorises acidified
KMnO4 and gives a grey precipitate with HgCl2; it
could be
(b)
NH4OH is a weak base
(a)
PbCl2
(b)
PbCl4
(c)
(NH4)2SO4 is a fertilizer
(c)
SnCl2
(d)
SnCl4
(d)
all of these
Which of the following statements are correct ?
38.
Which of the following product is formed when zinc
reacts with very dilute HNO3 ?
(a)
NO
(b)
NO2
(c)
NH4NO3
(d)
hydrogen
The blue colour produced in Lassaigne’s test of nitrogen is due to formation of
(a)
Na4[Fe(CN)6]
(b)
Fe3[Fe(CN)6]2
(c)
Fe2[Fe(CN)6]
(d)
NaFe[Fe(CN)6]
Einstein Classes,
37.
I—
A solution contains Hg , Pb , Cu , Ag+. Addition
of I— precipitates :
(a)
2+
CO32—
White fumes liberated on treating a white solid with
conc. H2SO4 and SiO2 leaves a white deposit on a
glass rod moistened with water. The white solid
could be
(a)
NaCl
(b)
NaF
(c)
NH4Cl
(d)
NaBr
Unit No. 102, 103, Vardhman Ring Road Plaza, Vikas Puri Extn., Outer Ring Road
New Delhi – 110 018, Ph. : 9312629035, 8527112111
CPC – 4
39.
Which of the following reaction(s) give(s) coloured
gases ?
(a)
40.
41.
43.
44.
45.
46.


K2Cr2O7 + KCl + H2SO4 (conc.) 
( B)


NaNO3 + H2SO4 (conc.) 
(c)
electrolysis of brine using mercury
cathode and graphite anode
CH 3COO ) 2 Pb
Yellow solution (C) (
  yellow ppt.
CH 3COOH
(D)
Which is correct ?
All of these
Which will give NO2 on heating ?
A
B
C
D
PbI2
(a)
NH4NO2
(b)
NH4NO3
(a)
AgCl
KCl
PbI2
(c)
NaNO3
(d)
LiNO3
(b)
AgCl
KCl
PbCrO4 Pb2Cr2O7
(c)
AgCl
CrCl2
PbCrO4 PbI2
(d)
CrCl3
AgCl
K2CrO4
Na2S2O3 is used in photography as a fixing agent
because of
(a)
its reducing property
(b)
its oxidising property
(c)
its sensitivity towards light
(d)
42.
Green coloured solute (A)
AgNO
3  white ppt. H
 Yellow
2 O 2 , KOH

(b)
(d)
47.
48.
PbCrO4
Solute A of Q.54 + K 2 Cr 2 O 7 + conc. H 2 SO 4
)2



E KOH

 F Pb
( CH
3COO

 G . Which is
CH 3COOH
correct set :
its ability to form a soluble complex with
Ag+ ions.
E
F
G
In alkaline medium, following will change colour
along with change in oxidation number
(a)
CrO2Cl2
(= C)
(= D)
(b)
Cl2
(= C)
(= D)
(a)
KMnO4
(b)
I2
(c)
CrO2Cl2
K2Cr2O7
PbI2
(c)
Cl2
(d)
all of these
(d)
none is true
Blue perchromic anhydride is obtained in ethereal
solution when H2O2 in ether is added to acidified
(with conc. H2SO4)K2Cr2O7 solution. It is due to
(a)
CrO3
(b)
H2CrO4
(c)
CrO5
(d)
H2Cr2O7
49.
50.
Which liberates Cl2 gas when conc. HCl is heated
with
(a)
KMnO4
(b)
K2Cr2O7
(c)
MnO2
(d)
all of these
NaNO3
(b)
Na2HPO4
(c)
KI
(d)
KCl

(a)
SnCl2
(b)
H 2S
(c)
Mg
(d)
all of these
Consider the following compounds
1.
Sulphur dioxide
2.
Hydrogen peroxide
3.
Ozone
Among these compounds, those which can act as
bleaching agents would include
Solute (X) is highly soluble in water. On adding
conc. H 2SO 4, there is no reaction and a clear
solution is obtained. X can be :
(a)
Yellow coloured solution of FeCl3 changes to green
coloured when X reacts with it, X is
51.
(a)
1 and 3
(b)
3
(c)
1 and 2
(d)
1, 2 and 3
Which of the following cations can be detected by
passing H2S in acid medium ?
 Y (g) + Z(g)
Solute X 
1.
Cu2+
2.
Pb2+
Aq. solution of X and Z gives white ppt. with AgNO3
soluble in aq. Y. Hence X can be
3.
Bi2+
4.
Zn2+
(a)
NaCl
(b)
NH4Cl
Select the correct answer using the codes given
below :
(c)
NH4NO3
(d)
NH4NO2
(a)
1, 2, 3 and 4
(b)
1 and 2
(c)
3 and 4
(d)
1, 2 and 3
Einstein Classes,
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New Delhi – 110 018, Ph. : 9312629035, 8527112111
CPC – 5
52.
53.
54.
55.
56.
57.
58.
59.
Which of the following statements(s) is/are correct
with reference to the ferrous and ferric ions ?
60.
In sodium extract test of organic compounds the
nirgoen of an organic compound is converted into
(a)
Fe3+ gives brown colour with potassium
ferricyanide
(a)
Sodamide
(b)
Sodium cyanide
(b)
Fe2+ gives blue precipitate with potassium
ferricyanide
(c)
Sodium nitrite
(c)
Fe3+ gives red colour with potassium thio
cyanate
(d)
Sodium nitrate
(d)
both (b) and (c) are correct
61.
Which of the following does not give the borax beas
test
(a)
Cr3+
(b)
Cu2+
(c)
Mn2+
(d)
Pb2+
62.
A mixture of acetone and methanol can be
separated by
(a)
Vacuum distillation
(b)
Steam distillation
(c)
Freactional distillation
(d)
None
63.
ClCH2COOH is heated with fuming HNO3 in the
presence of AgNO3 in Carius tube. After filtration
and washing the precipitate obtained is
(a)
AgNO3
(b)
AgCl
(c)
Ag2SO4
(d)
ClCH2COOAg
In Lassaigne’s test for N, S and halogens, the
organic compound is
(a)
Fused with sodium
(b)
Dissolved with sodamide
(c)
Extracted with sodamide
(d)
Fused with calcium
In Lassaigne’s test for nitrogen, the blue colour is
due to the formation of
Aniline is purified by
(a)
Ferric ferrocyanide
(a)
Steam distillation
(b)
Potassium ferrocyanide
(b)
Simple distillation
(c)
Sodium ferrocyanide
(c)
Vacuum distillation
(d)
Sodium cyanide
(d)
Extraction with a solvent
64.
In Kjeldahl’s method, nitrogen present is estimated
as
There are several criteria of purity of organic
compounds. Which is considered to be the best
(a)
Melting point
(a)
N2
(b)
NH3
(b)
Mixed melting point
(c)
NO2
(d)
None
(c)
Colour
(d)
Microscopic examination
Lassaigne’s test for the detection of nitrogen will
fail in case of
(a)
NH2CONH2
65.
(b)
H2NCONHNH2 · HCl
In Lassaigne’s test when both N and S are present,
blood red colour obtained is due to the formation
of
(c)
H2N · NH2 · 2HCl
(a)
Ferric ferrocyanide
(d)
C6H5NHNH2 · 2HCl
(b)
Ferric sulphocyanide
(c)
Ferric cyanide
(d)
None
Which reagent is useful in separating benzoic acid
from phenol
(a)
Dilute HCl
(b)
Dilute H2SO4
(c)
5% NaOH
(d)
5% NaHCO3
66.
A mixture of camphor and benzoic acid can be
separated by
A compound which does not give a positive test in
the Lassaigne’s test for N is
(a)
Sublimation
(b)
Chemical methods
(a)
Glycine
(c)
Fractional crystallisation
(b)
Phenyl hydrazine
(d)
Extraction with solvent
(c)
Urea
(d)
Azobenzene
Einstein Classes,
67.
In Kjeldahl’s method of estimation of nitrogen,
K2SO4 acts as
(a)
Oxidising agent
(b)
Catalytic agent
(c)
Hydrolysing agent
(d)
Boiling point elevator
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New Delhi – 110 018, Ph. : 9312629035, 8527112111
CPC – 6
68.
69.
70.
71.
72.
73.
74.
The function of boiling the sodium extract with
conc. HNO3 before testing for halogens is
(a)
To make solution clear
(b)
To descroy CN– and S2– ions which will
otherwide give ppt.
ANSWERS
1.
d
27.
b
53.
d
2.
c
28.
d
54.
c
3.
d
29.
c
55.
a
4.
b
30.
d
56.
b
5.
d
31.
d
57.
c
6.
c
32.
d
58.
d
7.
c
33.
a
59.
d
8.
b
34.
d
60.
b
9.
a
35.
a
61.
b
In Duma’s method for determining the nitrogen
content of an organic compound, the nitrogen
content is determined in the form of
10.
a
36.
d
62.
a
11.
a
37.
c
63.
a
(a)
Gaseous NH3
(b)
NaCN
12.
d
38.
b
64.
b
(c)
Gaseous N2
(d)
(NH4)2SO4
13.
c
39.
d
65.
b
14.
b
40.
d
66.
b
(c)
To make the solution acidic
(d)
The convert Fe2+ to Fe3+
The sulphur present in an organic compound is
oxidised by fuming nitric acid into
(a)
SO2
(b)
H2SO4
(c)
H 2S
(d)
S
An organic compound containing C, H and N have
the percentage 40, 13.33 and 46.67 respectively. Its
empricial formula may be
(a)
C2H 7N
(b)
C2H7N2
(c)
CH4N
(d)
CH5N
0.14g of an acid required 12.5 mL of 0.1N-NaOH
for complete neutralisation. The equivalent weight
of the acid is
(a)
45
(b)
56
15.
a
41.
d
67.
d
(c)
63
(d)
112
16.
d
42.
d
68.
b
17.
b
43.
c
69.
b
18.
d
44.
d
70.
c
19.
b
45.
b
71.
c
20.
d
46.
b
72.
d
21.
b
47.
d
73.
d
22.
b
48.
a
74.
b
23.
d
49.
d
24.
b
50.
c
25.
b
51.
d
26.
a
52.
d
In the estimation of nitrogen by Duma’s method
1.18 g of an organic compound gave 224 mL of N2
at NTP. The percentage of nitrogen in the compound
is about
(a)
20.0
(b)
11.8
(c)
47.5
(d)
23.7
0.5 g of an organic compound containing nitrogen
on Kjeldahlising required 29 mL of N/5 H2SO4 for
complete neutralisation of ammonia. The
percentage of nitrogen in the compound is
(a)
34.3
(b)
16.2
(c)
21.6
(d)
14.8
Einstein Classes,
Unit No. 102, 103, Vardhman Ring Road Plaza, Vikas Puri Extn., Outer Ring Road
New Delhi – 110 018, Ph. : 9312629035, 8527112111
CPC – 7
TEST YOURSELF
1.
2.
3.
HgCl2 reacts with KI forming X. X dissolved in excess of KI to form Y, X and Y are :
(a)
HgI2, K2HgI4
(b)
Hg2I2, K2HgI4
(c)
HgI2, HgI3—
(d)
Hg2I2, K2HgI4
This radical can be identified by Borax Bead test
(a)
Mg2+
(b)
Ca2+
(c)
Cu+
(d)
Cu2+
NH 4 + salt gives brown colour with alkaline
Nesseler’s reagent to form iodide of Millon’s base
with formula :
(a)
4.
(b)
NH2 – Hg – HgI
(c)
HgI42—
(d)
NH2 – Hg – I
When KOH is added to KMnO4, green colour is
formed. This is due to
(a)
(c)
5.
6.
7.
8.
9.
10.
MnO7
MnO
2—
4
(b)
MnO2
(d)
Mn2+
The sulphur present in an organic compound is
oxidised by fuming nitric acid into
(a)
H 2S
(b)
SO2
(c)
SO3
(d)
H2SO4
Which will give N2O on heating ?
(a)
NH4NO2
(b)
NH4NO3
(c)
NaNO3
(d)
LiNO3
Which salts are determined by idometric titration
(a)
KMnO4
(b)
K2Cr2O7
(c)
CuSO4
(d)
all of these
Which compound does not dissolve in hot dilute
HNO3 ?
(a)
HgS
(b)
PbS
(c)
CuS
(d)
CdS
In Kjeldahl’s method nitrogen present is
quantitatively converted to
(a)
N2
(b)
(NH4)2SO4
(c)
NO2
(d)
None
Which of the following reagents is useful for
separating aniline from a mixture of aniline and
nitrobenzene
(a)
NaOH(aq)
(b)
H2 O
(c)
NaHCO3(aq)
(d)
HCl(aq)
Einstein Classes,
ANSWERS
1.
a
6.
b
2.
d
7.
d
3.
a
8.
a
4.
c
9.
b
5.
d
10.
d
Unit No. 102, 103, Vardhman Ring Road Plaza, Vikas Puri Extn., Outer Ring Road
New Delhi – 110 018, Ph. : 9312629035, 8527112111