1 . 2475 g of crystalline copper sulphate was dissolved in water and excess of KI was added. The liberated iodine consumed 50 mL N 10 Na 2 S 2 O 3 solution to reach the end point of the titration. Calculate the number of water molecules of hydration in crystalline copper sulphate salt.

4 I - + 2 Cu 2 + → Cu 2 I 2 + I 2 I 2 + 2 S 2 O 3 2 - → 2 I - + S 4 O 6 2 - meq. of Hypo = meq. of I 2 mili-equivalent of I 2 = 50 × 1 10 = 5 meq. of I 2 = meq.of hydrated CuSO 4 Number of moles of Hydrated CuSO 4 = 5 × 1 × 10 - 3 = 0 . 005 moles Mass of Hydrate Copper Sulphate = 1 . 2475 g Molar Mass of Hydrated Copper Sulphate = 1 . 2475 0 . 005 = 249 . 5 g / mol Molar Mass of Anhydrous Copper Sulphate = 159 . 5 g / mol Molar Mass of water = 18 g / mol Number of water molecules of hydration in crystalline copper sulphate = 249 . 5 - 159 . 5 18 = 90 18 = 5 .

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$35 mL$ sample of hydrogen peroxide gives off $500 mL$ of $O_{2}$ at $27^{\circ} C$ and $1$ $atm$ pressure. Determine volume strength of $H_{2} O_{2}$ sample.

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Important Questions on Redox Reactions

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Beta Question Bank for Engineering: Chemistry>Chapter 6 - Redox Reactions>EXERCISE-2>Q 7

0.80 g

of sample of impure potassium dichromate was dissolved in water and made upto

500 mL

solution.

25 mL

of this solution treated with excess of

KI

in acidic medium and

I_{2}

liberated required

24 mL

of a sodium thiosulphate solution.

30 mL

of this sodium thiosulphate solution required

15 mL

\frac{N}{20}

solution of pure potassium dichromate. What was the percentage of

K_{2} {Cr}_{2} O_{7}

in given sample?

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Beta Question Bank for Engineering: Chemistry>Chapter 6 - Redox Reactions>EXERCISE-2>Q 8

The following reaction describes the rusting of iron,

4 Fe + 3 O_{2} ⟶ 4 {Fe}^{3 +} + 6 O^{2 -} .

Which one of the following statements are correct:

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Beta Question Bank for Engineering: Chemistry>Chapter 6 - Redox Reactions>EXERCISE-2>Q 10

How many litres of

{Cl}_{2}

S . T . P .

will be liberated by oxidation of

NaCl

with

10 g {KMnO}_{4} : -

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Beta Question Bank for Engineering: Chemistry>Chapter 6 - Redox Reactions>EXERCISE-2>Q 12

A mixture of H₂SO₄ and H₂C₂O₄ (Oxalic acid) and some inert impurity weighing 3.185 g was dissolved in water and the solution made up to 1 litre, 10 mL of this solution required 3 mL of 0.1 N NaOH for complete neutralization. In another experiment, 100 mL of the same solution in hot condition required 4 mL of 0.02 M KMnO₄ solution for complete reaction. The wt. % of H₂SO₄ in the mixture was:

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Beta Question Bank for Engineering: Chemistry>Chapter 6 - Redox Reactions>EXERCISE-3>Q 14

1.0 g

sample of

{Fe}_{2} O_{3}

solid of

55.2 %

purity is dissolved in acid and reduced by heating the solution with zinc dust. The resultant solution is cooled and made up to

100.0 mL .

An aliquot of

25.0 mL

of this solution requires

17.0 mL

0.0167 M

solution of an oxidant for titration. Calculate the number of moles of electrons taken up by the oxidant in the reaction of the above titration.

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Beta Question Bank for Engineering: Chemistry>Chapter 6 - Redox Reactions>EXERCISE-3>Q 15

{KMnO}_{4}

oxidizes

X^{n +}

ion to

{XO}_{3}^{-},

itself changing to

{Mn}^{2 +}

in acid medium.

2.68 \times 10^{- 3}

mole

X^{n +}

requires

1.61 \times 10^{- 3}

mole

{MnO}_{4}^{-},

if the weight of

1 g

equivalent of

{XCl}_{n}

56 .

Report the value of

\frac{X}{n},

where

X

is the molar mass of

X^{n +} .

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Beta Question Bank for Engineering: Chemistry>Chapter 6 - Redox Reactions>EXERCISE-3>Q 23

Nitrous acid can act both as an oxidising as well as reducing agent.

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Beta Question Bank for Engineering: Chemistry>Chapter 6 - Redox Reactions>EXERCISE-4>Q 1

1.2475 g

of crystalline copper sulphate was dissolved in water and excess of

KI

was added. The liberated iodine consumed

\frac{50 mL N}{10 {Na}_{2} S_{2} O_{3}}

solution to reach the end point of the titration. Calculate the number of water molecules of hydration in crystalline copper sulphate salt.

35 mL sample of hydrogen peroxide gives off 500 mL of O2 at 27∘C and 1 atm pressure. Determine volume strength of H2O2 sample.

Important Questions on Redox Reactions

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$35 mL$ sample of hydrogen peroxide gives off $500 mL$ of $O_{2}$ at $27^{\circ} C$ and $1$ $atm$ pressure. Determine volume strength of $H_{2} O_{2}$ sample.