HARD

Earn 100

An aqueous solution of $NaCl$ on electrolysis gives $H_{2} (g), {Cl}_{2} (g) and NaOH$ according to the reaction:

$2 {Cl}^{-} (aq) + 2 H_{2} O \to 2 {OH}^{-} (aq) + H_{2} (g) + {Cl}_{2} (g) .$

A direct current of $25 amperes$ with a current efficiency of $62 %$ is passed through $20 litres$ of $NaCl$ solution ( $20 %$ by weight). The reaction taking place at the anode and the cathode are:

Reaction at anode: $2 {Cl}^{-} \to {Cl}_{2} + 2 e^{-}$

Reaction at cathode: $2 H_{2} O + 2 e^{-} \to H_{2} + 2 {OH}^{-}$

The time it will take to produce $1 kg$ of ${Cl}_{2}$ and the molarity of the solution with respect to hydroxide ion would be (if it is assumed that there is no loss because of evaporation):

50% studentsanswered this correctly

Important Questions on Electrochemistry

MEDIUM

Chemistry>Physical Chemistry>Electrochemistry>Electrolytic Cells and Electrolysis

Oxidation of succinate ion produces ethylene and carbon dioxide gases. On passing

0.2

Faraday electricity through an aqueous solution of potassium succinate, what is the total volume of gases (at both cathode and anode) at STP (

1 atm

and

273 K

EASY

Chemistry>Physical Chemistry>Electrochemistry>Electrolytic Cells and Electrolysis

The density of metal and equivalent weight of a metal are

10.5 g {cm}^{- 3}

and

100

, respectively. The time required for a current of

3 amp

to deposit a

0.005 mm

thick layer of the same metal on an area of

80 {cm}^{2}

is closest to

HARD

Chemistry>Physical Chemistry>Electrochemistry>Electrolytic Cells and Electrolysis

How long (approximate) should water be electrolysed by passing through

100

amperes

current so that the oxygen released can completely burn

27.66 g

of diborane? (Atomic weight of

B = 10.8 u

)

MEDIUM

Chemistry>Physical Chemistry>Electrochemistry>Electrolytic Cells and Electrolysis

The weight of silver (at.wt.

= 108

) displaced by a quantity of electricity which displaces

5600 m L

O_{2}

STP

will be

EASY

Chemistry>Physical Chemistry>Electrochemistry>Electrolytic Cells and Electrolysis

The number of electrons delivered at the cathode, during electrolysis by a current of

1 ampere in 60 seconds

is (charge on electron

= 1.60 \times 10^{- 19} C

)

MEDIUM

Chemistry>Physical Chemistry>Electrochemistry>Electrolytic Cells and Electrolysis

When

0.1 m o l {M n O}_{4}^{2 -}

is oxidized the quantity of electricity required to completely

M n O_{4}^{2 -}

M n O_{4}^{-}

MEDIUM

Chemistry>Physical Chemistry>Electrochemistry>Electrolytic Cells and Electrolysis

A current of $10.0 A$ flows for $2.00 h$ through an electrolytic cell containing a molten salt of metal $X$ . This results in the decomposition of $0.250 mol$ of metal $X$ at the cathode. The oxidation state of $X$ in the molten salt is:

$(F = 96, 500 C)$

EASY

Chemistry>Physical Chemistry>Electrochemistry>Electrolytic Cells and Electrolysis

The quantity of electricity needed to separately electrolyse

1 M

solution of

{ZnSO}_{4}, {AlCl}_{3}

and

{AgNO}_{3}

completely is in the ratio of

MEDIUM

Chemistry>Physical Chemistry>Electrochemistry>Electrolytic Cells and Electrolysis

When 9.65 ampere current was passed for 1.0 hour into nitrobenzene in acidic medium, the amount of p-aminophenol produced is:

EASY

Chemistry>Physical Chemistry>Electrochemistry>Electrolytic Cells and Electrolysis

For electroplating,

1.5 amp

current is passed for

250 s

through

250 m L of 0.15 M

solution of

M S O_{4} .

Only

85 %

of the current was utilised for electrolysis. The molarity of

M S O_{4}

solution after electrolysis is closest to [Assume that the volume of the solution remain constant]

MEDIUM

Chemistry>Physical Chemistry>Electrochemistry>Electrolytic Cells and Electrolysis

An aqueous solution of

{CuSO}_{4}

is subjected to electrolysis using inert electrodes. The

pH

of the solution will

MEDIUM

Chemistry>Physical Chemistry>Electrochemistry>Electrolytic Cells and Electrolysis

A constant current (0.5 amp) is passed for 1 hour through (i) aqueous

A g N O_{3}

. (ii) aqueous

C u S O_{4}

and (iii) molten

A l F_{3}

, separately. The ratio of the mass of the metals deposited on the cathode is

[M_{Ag}, M_{Cu}, M_{Al}

are molar masses of the respective metals

]

MEDIUM

Chemistry>Physical Chemistry>Electrochemistry>Electrolytic Cells and Electrolysis

One litre solution of

{MgCl}_{2}

is electrolyzed completely by passing a current of

1 A

for

16 \min 5

sec. The original concentration of

{MgCl}_{2}

solution was (Atomic mass of

Mg = 24

)

EASY

Chemistry>Physical Chemistry>Electrochemistry>Electrolytic Cells and Electrolysis

A solution of

N i {(N O_{3})}_{2}

is electrolyzed between platinum electrode

0.1

Faraday electricity. How many mole of

N i

will be deposited at the cathode?

MEDIUM

Chemistry>Physical Chemistry>Electrochemistry>Electrolytic Cells and Electrolysis

The number of Faradays(F) required to produce

20 g

of calcium from molten

{CaCl}_{2}

(Atomic mass of

Ca = 40 g {mol}^{- 1}

) is

MEDIUM

Chemistry>Physical Chemistry>Electrochemistry>Electrolytic Cells and Electrolysis

What time in sec is required for depositing all the silver present in

125 ml

1 M {AgNO}_{3}

solution by passing a current of

241.25

A (Given

1 F = 96500 C

)

MEDIUM

Chemistry>Physical Chemistry>Electrochemistry>Electrolytic Cells and Electrolysis

0.5 F

of electricity is passed through

500 mL

of copper sulphate solution. The amount of copper which can be deposited will be

HARD

Chemistry>Physical Chemistry>Electrochemistry>Electrolytic Cells and Electrolysis

Calculate the molarity of a solution containing

5 g

N a O H

dissolved in the product of a

H_{2} - O_{2}

fuel cell operated at

1 A

current for

595.1

hours.

(Assume

1 F = 96500 C / m o l

of electrons and molecular weight of

N a O H

40 g m o l^{- 1}

)

EASY

Chemistry>Physical Chemistry>Electrochemistry>Electrolytic Cells and Electrolysis

During the electrolysis of molten sodium chloride, the time required to produce

0.10 mol

of chlorine gas using a current of

3 amperes

EASY

Chemistry>Physical Chemistry>Electrochemistry>Electrolytic Cells and Electrolysis

Two Faraday of electricity is passed through a solution of

C u S O_{4}

. The mass of copper deposited at the cathode is: (Atomic mass of Cu = 63.5 amu)

Important Questions on Electrochemistry

Learn and Prepare for any exam you want !