Faraday's Second Law

Q.

Copper sulphate solution (250 ml) was electrolyzed using a platinum anode and copper cathode. A constant current of 2 mA was passed for 16 minute. It was found that after electrolysis, the absorbance of the solution was reduced to 50% of its original value. Calculate the concentration of copper sulphate ion in the solution to begin with.

1. 2.67 x 10^-2 M

2. 4.6 x 10^-8 M

3. 9.5 x 10^-3 M

4. 7.95 x 10^-5 M

Q. When 0.1 mol $Mn{O}_4^{2-}$ is oxidised, quantity of electricity required to completely oxidise $Mn{O}_4^{2-}$ to $Mn{O}_4^{-}$ is

1. 96500 C
2. 2 $\times$ 96500 C
3. 9650 C
4. 96.50 C

Q.

The atomic weight of Al is 27. When a current of 5 Faradays is passed through a solution of Al⁺³ions, the weight of Al deposited is

1. 36 gm

2. 45 gm

3. 39 gm

4. 27 gm

Q. During electrolysis, 25 g of a metal is deposited on the cathode of a metal nitrate solution by a current of 5 A passing for 4 hours. If the atomic weight of the metal is 100 amu, find the valency of the metal in the metal nitrate:

1. 1
2. 2
3. 3
4. 4

Q. A current of $0.5A$ is passed through molten $AlC{l}_3$ for 40 min. Calculate the mass of aluminium deposited at the cathode (Gram Atomic Mass of Al = 27g)

1. 0.111 gm
   
2. 0.110 gm
   
3. 0.114 gm
   
4. 0.112 gm

Q.

A lead storage battery containing 5.0L of $H_{2}S{O}_4$ solution is operated for $9.65\times {10}^{5}s$ with a steady current of 100 mA. Assuming volume of the solution remains constant, normality of $H_{2}S{O}_4$ will :

1. decrease by 0.40

2. increase by unity

3. remain unchanged

4. increase by 0.20

Q.

Salts of A (atomic mass 15), B (atomic mass 27) and C (atomic mass 48) were electrolyzed using the same amount of charge. It was found that when 4.5 g of A was deposited, the masses of B and C deposited were 2.7 g and 9.6 g. The valences of A, B and C were respectively

1. 1, 3 and 2

2. 3, 1 and 3

3. 3, 1 and 2

4. 2, 3 and 2

Q. The amount of zinc required to produce $1.12\text{mL}$ of $H_2$ at STP on treatment with $dil.HCl$ will be: (Given: Molar mass of $Zn$= $65g/mol$)

1. $60\text{g}$
2. $0.65\text{g}$
3. $32.5\times {10}^{-4}\text{g}$
4. $6.5\text{g}$

Q. How many coulombs are required for the oxidation of 1 mol of $H_2{O}_2$ to $O_2?$

1. $9.65\times {10}^{4}C$
2. $93000C$
3. $1.93\times {10}^5$
4. $19.3\times {10}^{2}C$

Q. Three ampere current was passed through an aqueous solution of an unknown salt of metal M for 1 hour. 2.997 gm of $M^{n+}$ was deposited at cathode. The value of n is (Atomic weight of M = 106.4)

1. 1
2. 2
3. 3
4. 4

Q.

An acidic solution of $C{u}^{2+}$ salt containing 0.4 g of $C{u}^{2+}$ (CuSO₄) is electrolysed until all the Cu is deposited. The electrolysis is continued for seven more minutes with the volume of solution kept at 100 ml and the current at 1.2 Ampere. Calculate volume of gases evolved at N.T.P at anode during entire electrolysis.

1. 44.56 ml

2. 99.68 ml

3. 34 ml

4. 12 ml

Q.

In electrolytic reduction of a nitroarene with 50% current efficiency, 20.50 g of the compound is reduced by $2\times 96500$ C of electric charge. The molar mass of the compound is :

1. 20.50 g

2. 10.25 g

3. 123.00 g

4. 61.50 g

Q. A quantity of electricity required to reduce 12.3 g of nitrobenzene to aniline arising $50\%$ current efficiency is:

1. 1158000C
2. 579000C
3. 231600C
4. 289500C

Q. On passing one faraday of electricity through the electrolytic cells containing $A{g}^{+},N{i}^{+2}$ and $C{r}^{+3}$ ions solution, the deposited $Ag(At.wt.=108),Ni(At.wt.=59)andCr(At.wt.=52)$ is

$\begin{array}{cccc}& Ag\left(ingm\right)& Ni\left(ingm\right)& Cr\left(ingm\right)\\ a)& 108& 59& 52\\ b)& 108& 29.5& 17.3\\ c)& 36& 19.6& 17.3\\ d)& 108& 108& 108\end{array}$

1. a
2. b
3. c
4. d

Q.

When 9.65 coulombs of electricity is passed through a solution of silver nitrate

(atomic weight of taking as 108) the amount of silver deposited is

[EAMCET 1992; KCET 2000]

1. 10.8 mg
2. 5.4 mg
3. 16.2 mg
4. 21.2 mg

Q. Three ampere current was passed through an aqueous solution of an unknown salt of metal M for 1 hour. 2.997 gm of $M^{n+}$ was deposited at cathode. The value of n is (Atomic weight of M = 106.4)

1. 1
2. 2
3. 3
4. 4

Q. A quantity of electricity required to reduce 12.3 g of nitrobenzene to aniline arising $50\%$ current efficiency is:

1. 1158000C
2. 231600C
3. 579000C
4. 289500C

Q. On passing one faraday of electricity through the electrolytic cells containing $A{g}^{+},N{i}^{+2}$ and $C{r}^{+3}$ ions solution, the deposited $Ag(At.wt.=108),Ni(At.wt.=59)andCr(At.wt.=52)$ is

$\begin{array}{cccc}& Ag\left(ingm\right)& Ni\left(ingm\right)& Cr\left(ingm\right)\\ a)& 108& 59& 52\\ b)& 108& 29.5& 17.3\\ c)& 36& 19.6& 17.3\\ d)& 108& 108& 108\end{array}$

1. a
2. b
3. c
4. d

Q.

The atomic weight of Al is 27. When a current of 5 Faradays is passed through a solution of Al⁺³ions, the weight of Al deposited is

1. 27 gm

2. 36 gm

3. 45 gm

4. 39 gm

Q. A direct current deposits $54g$ of silver during electrolysis. How much amount of aluminium would be deposited from aluminium chloride solution by the same amount of electricity?
( $\text{Atomic mass of Ag}=108g/mol$)
($\text{Atomic mass of Al}=27g/mol$)

1. $4.5g$
2. $5.4g$
3. $54g$
4. $2.7g$