7/31/2019 Volumetric Final
41/41
Volumetric Assignment
03. A PQ; B P;C RS; D RT 04. A P, T;B Q, S; C R;D P,R
COMPREHENSIONS
Comprehension:-I
The mass percentage of MnO2
in the given sample of pyrolusite was determined byreacting it
with As
2O
3in acid medium. A sample of 0.3g was ground and boild with
75
mL of 0.0125M As2O
3solution. On completing the reaction the solution is cooled
and
titrated against 2.4 102 M KMnO4
and it required 12.5 mL of the solution to reach
the end point (At mass of As = 75, Mn = 55)Answer the
following:-
01. The equivalent mass of As2O
3in the reactions with MnO
2as well as KMnO
4in acid
medium.
a) 198 b) 99 c) 49.5 d) 24.75
02. Number of equivalents of As2O
3reacted with acidified KMnO
4
a) 1.5 b) 1.5 103 c) 0.15 d) 1.5 102
03. Percentage of MnO2
in the given sample of pyrolusite
a) 24.4 b) 32.6 c) 65.2 d) 16.3
Comprehension:-II
Hydrogen peroxide solution (20 mL) reacts quantitatively with a
solution of KMnO4
(20mL) acidif ied with dilute H
2SO
4. The same volume of the KMnO
4solut ion is just
decolourised by 10 mL of MnSO4
in neutral medium simultaneously forming a darkbrown precipitate
of hydrated MnO
2. The brown precipitate is dissolved in 10 mL of 0.2
M sodium oxalate under boiling condition in the presence of
dilute H2SO
4.
Answer the following:
04. Mass of MnO2
formed
a) 4.35g b) 0.174 g c) 0.348g d) 3.44 g
05. As per th e reaction between KMnO4
and MnSO4
in neutral medium, the equivalentmass of KMnO
4(M. Mass of KMnO
4= M)
a)M
3b) M c)
M
5d)
M
2
06 . Molar it y of H2O
2solution
a) 0.2 b) 0.4 c) 0.8 d) 0.1
Comprehension:-III
A 3.0 g sample containing Fe3O
4, Fe
2O
3and an inert impure substance is treated with
excess of KI solution in presence of dilute H2SO
4.The entire iron is converted to Fe2+
along with the liberation of iodine. The resulting solution is
diluted to 100 mL. A 20 mLof the dilute solution requires 11 mL of
0.5 M Na
2S
2O
3solution to reduce the iodine
present.A 50 mL of the diluted solution after complete
extraction of iodine required
12.8 mL of 0.25 M KMnO4 solution in dilute H 2SO4 medium for the
oxdation of Fe2+.Answer the following:-07. Total no of meq of Iron
present
a) 27.5 b) 32.0 c) 13.75 d) 1608. Mass of Fe
3O
4present in the given sample
a) 2.088 g b) 1.044 g c) 3.132 g d) 0.522 g09 Percentage by mass
of Fe O in the given sample
