Electrolytic Cells and Electrolysis

IMPORTANT

Electrolytic Cells and Electrolysis: Overview

In this topic, we will learn about electrolytic cells and electrolysis. Here we will learn that an electrolytic cell drives a spontaneous redox reaction through electrical energy. Electrolysis, however, is a technique that uses direct current.

Important Questions on Electrolytic Cells and Electrolysis

HARD
IMPORTANT

What amount of silver will be deposited by passing 2F electricity through two solutions containing 0.1 M AgNO3 and 0.2 M AgNO3.

HARD
IMPORTANT

The image below shows electrolysis of an electrolyte using a DC voltage source.

Question Image

Based on this, Which of the following statements is/are correct?

(i) The solution remains electrically neutral during electrolysis.

(ii) Electrons flow from the current source towards the solution at one electrode, and an equal number of electrons flow away from the solution at the other electrode.

(iii) The number of positive ions moving towards one electrode is always equal to the number of negative ions moving towards the other electrode.

EASY
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Write a anodic reaction involved in the electrolysis of brine solution using mercury electrode.

MEDIUM
IMPORTANT

Write the reactions that occur on anode and cathode during electrolysis of dilute sulphuric acid.

MEDIUM
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The product obtained at cathode during electrolysis of dilute sulphuric acid is:

MEDIUM
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The product obtained at cathode during electrolysis of dilute sulphuric acid is hydrogen gas.

MEDIUM
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The product obtained at anode during electrolysis of dilute sulphuric acid is hydrogen gas.

MEDIUM
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Electrolysis of NaCl solution gives _____ at anode. (chlorine / oxygen)

MEDIUM
IMPORTANT

A sample of Al2O3, dissolved in a molten fluoride bath, is electrolysed using a current of 1.20 A. What is the rate of production of Al in gram/hour ?

Give your answer by multiplying with 1000 and rounding off to three significant figures.

HARD
IMPORTANT

A solution containing Cu(I), Ni and Zn cyanide complexes was electrolysed and a deposit of 0.175 g was obtained. The deposit contained 72.8% Cu, 4.3%Ni and 22.9% Zn. No other element was released. Calculate the number of coulombs passed through the solution. (At. wt. Cu = 63.5, Zn = 65, Ni = 59 )

Report the answer by rounding off to three significant figures

MEDIUM
IMPORTANT

If 40 mL of 0.125 M of NiSO4 solution is electrolysed by a current of 0.05 amp for 40 minutes,

 The number of grams of the product deposited at the cathode is Q X 10-3, Report the value of Q in 2 significant figures.

Consider,1F=96500 coulomb and atomic weight of Ni is 58.7g

HARD
IMPORTANT

Lake Cayuga has a volume of water estimated to be 8.2×1012 L. A power station not so far above Cayuga's waters produces electricity at the rate of 1.5×106 coulombs per second at an appropriate voltage. How long(in years) would it take to electrolyse the lake?

If the answer is X×104. Give the value of X?

HARD
IMPORTANT

How long (in sec) should a current of 0.5 amp be passed through 50 mL of a 0.10 M NaCl solution in order to make its pH=12, assuming that no volume changes?

Round-off the answer to the nearest integer.

HARD
IMPORTANT

One hundred millilitres of 0.8 M copper sulphate solution is electrolysed for 30 minutes by passing a current of 5 amp. Calculate the amount of copper sulphate in grams in the solution.

Round off answer to the nearest integer value.

HARD
IMPORTANT

Electric current is passed through two cells 'A'  'B' in series. Cell 'A' contains an aqueous solution of Ag2SO4 and platinum electrodes. The cell  'B' contains an aqueous solution of CuSO4 and Cu electrodes. The current is passed till 1.6 g of oxygen is liberated at the anode of cell 'A'.

Calculate the mass of silver deposited(in grams) at the cathodes (Ag=108, Cu=63.5) (Round off answer to the nearest integer value).

MEDIUM
IMPORTANT

For the electrolytic production of NaClO4 from NaClO3 as per reaction:

ClO3-+H2OClO4-+2H++2e-

How many faradays of electricity would be required to produce 1 mole of NaClO3 ?

HARD
IMPORTANT

50 mL of a 0.1 M CuSO4 solution is electrolysed for 12 minutes at a current of 0.06 amp. If Cu is produced at one electrode and O2 at the other, what will be the pH of the final solution? For HSO4-=H++SO42-, Kdiss =1·3×10-2,

Report your answer by multiplying the PH value obtained in to 10 and rounding off the value to two significant figures.

MEDIUM
IMPORTANT

How many hours are required for a current of 3 amp to decompose electrolytically 18 g of water? 

Express your answer by rounding off the value to two significant figures.

MEDIUM
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During the electrolysis of aqueous solution of CuSO4 by using platinum electrodes _____ will deposit at cathode.(Copper/Oxygen)

MEDIUM
IMPORTANT

During electrolysis of a solution of AgNO3, 9650 coulombs of charge is passed through the solution. The mass of silver deposited on the cathode is _____ g.