elements, their occurrence and extraction

MUNISH KAKAR’s INSTITUTE OF CHEMISTRY
Stoichiometric Calculations
Q1.
Calculate the equivalent weight of permanganate ion ( MnO4 ) as per following reactions;

H
(a) MnO4 
 Mn 2

(M/5)
OH
(c) MnO4 
 MnO42 
Q2.
H 2O
(b) MnO4 
 MnO2
(M/1)
Assume molar mass of ( MnO4 ) to be M
How many mL of 0.05 M MnO4 (acidic) are required to oxidize 0.2 mole of Fe2 ?
MnO4  Fe 2 
 Mn 2 
Q3.
(M/3)
Fe3
(800 mL)
20 mL of 0.2M Mn2 are completely oxidized by 16 mL of MnO4 of unknown normality
each forming Mn4+ oxidation state. Find out the normality of MnO4 .
Q4.
(0.2 N)
1g of H2O2 solution containing X% H2O2 by weight requires X mL of MnO4 for complete
oxidation in acid medium. Calculate normality of MnO4 solution.
MnO4  H 2O2 
 Mn 2 
Q5.
(0.58 N)
O2
An element A in a compound ABD has an oxidation no. A n  . It is oxidized by Cr2O72- in
acid medium. In an experiment 1.68  10-3 mole of Cr2O72 was required for 3.26  10-3
mole of the compound ABD. Calculate new oxidation state of A.
Q6.
(3-n)
Find out the % of oxalate ion in given sample of oxalate salt of which 0.3 g dissolved in
100 mL of water required 90 mL of 0.05 N MnO4 for complete oxidation as per reaction ;
MnO4  C2O42 
 Mn 2  CO2
Q7.
(66%)
MnO4 oxidizes Xn+ ion to XO3 , itself changing to Mn2+ in acid solution. 2.68  10-3 mole
of Xn+ requires 1.61  10-3 mole of MnO4 . What is the value of n ?
Q8.
(n = 2)
A solution of 0.1 M MnO4 is used for the reaction :
S2O32– + 2 MnO4 + H2O  MnO2 + SO42– + OH–
(2.67 mL)
What volume of solution in mL will be required to react with 0.001 mole of S2O32 ?
Q9.
30 mL of a solution containing 9.15 g/litre of an oxalate K xHy(C2O4)z.nH2O are required for
titrating 27 mL of 0.12 N NaOH and 36 mL of 0.12 N KMnO 4 separately. Calculate X, Y, Z
and n. assume all H-atoms are replaceable and X, Y, Z are in the simple ratio of g-atoms.
[ KH3(C2O4)2.2H2O ]
Q10. 0.98 g of polybasic acid(mol.wt.98) requires 30 mL of 0.5 M Ba(OH) 2 for complete
neutralization. The basicity of acid is….
(3)
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