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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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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Important Questions on Redox Reactions

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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.

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Beta Question Bank for Engineering: Chemistry>Chapter 6 - Redox Reactions>EXERCISE-4>Q 2

1 g

sample of

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

containing some inert material was entirely reduced with conc.

HCl

. The chlorine, liberated was passed through hot solution of

NaOH

80 ° C

, and it completely diproportionates to form

{ClO}_{3}^{-}

and

{Cl}^{-}

. This

{NaClO}_{3}

was isolated and its reduction with

KI

(aq) liberated iodine, giving

Cl

. The iodine, thus liberated required

100 mL

of decinormal hypo solution for complete titration. What is the percentage, purity of the dichromate sample?

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Beta Question Bank for Engineering: Chemistry>Chapter 6 - Redox Reactions>EXERCISE-4>Q 3

2.5 g

of mixture of crystalline oxalic acid

(H_{2} C_{2} O_{4} . 2 H_{2} O)

and sodium oxalate

({Na}_{2} C_{2} O_{4})

was dissolved in

100 mL

of water.

50 mL

of this solution was titrated against

\frac{N}{10 NaOH}

solution when

119.05 mL

of the base was found necessary to reach the end point with phenolphthalein as the indicator.

1 g

of the mixture was dissolved in water and the solution titrated against

\frac{N}{10 {KMnO}_{4}}

in the presence of dil.

H_{2} {SO}_{4}

. What is the volume of

{KMnO}_{4}

needed for getting the end point with

0.5 g

of the mixture?

The following reaction describes the rusting of iron, 4Fe+3O2⟶4Fe3++6O2-. Which one of the following statements are correct:

Important Questions on Redox Reactions

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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: