Application of Electrolysis

Q. The number of carbon atoms per unit cell of diamond is:

1. $6$
2. $1$
3. $4$
4. $8$

Q.

Explain faradays first law of electrolysis in details.

Q.

Potassium chlorate is prepared by the electrolysis of KCl in basic solution

6OH^– + Cl^– -> ClO₃^– + 3H₂O + 6e^–

If only 60% of the current is utilized in the reaction, the time (rounded to the nearest hour) required to produce 10g of KClO₃ using a current of 2A is ………….

(Given: F = 96, 500 C mol^-1; molar mass of KClO₃=122g mol^-1)

Q. How many unit cells are present in a cube-shaped ideal crystal of NaCl of mass 1.00 g
[Atomic masses: Na=23, Cl=35.5]

1. 2.57 x 10²¹ unit cells
2. 5.14 x 10²¹ unit cells
3. 1.28 x 10²¹ unit cells
4. 1.71 x 10²¹ unit cells

Q. How many molecules are present in 9g of water?

1. 6.022$\times$ ${10}^{23}$
2. 3.011$\times$ ${10}^{23}$
3. 6.022$\times$ ${10}^{25}$
4. 3.011$\times$ ${10}^{20}$

Q.

How many oxygen atoms are present in 50g of $CaC{o}_3$ ?

1. 3.011 $\times$ ${10}^{23}$

2. 6.022 $\times$ ${10}^{23}$

3. 9.033 $\times$ ${10}^{23}$

4. 12.044 $\times$ ${10}^{23}$

Q. The standard reduction potentials of $\text{Ag, Cu, Co and Zn}$ is $0.799V,0.337V,-0.277V,-0.762V$ respectively. Which of the following cells will have maximum cell e.m.f. value?

1. $Zn|Z{n}^{2+}\left(1M\right)||C{u}^{2+}\left(1M\right)|Cu$
2. $Zn|Z{n}^{2+}\left(1M\right)||A{g}^{+}\left(1M\right)|Ag$
3. $Cu|C{u}^{2+}\left(1M\right)||A{g}^{+}\left(1M\right)|Ag$
4. $Zn|Z{n}^{2+}\left(1M\right)||C{o}^{2+}\left(1M\right)|Co$

Q.

Describe the electrolysis of molten solution of Lead bromide.

Q.

Calculate the emf of the following cell at ${25}^{\circ }C$.
$Ag\left(s\right)|AgN{O}_3\left(0.01{\text{mol kg}}^{-1}\right)||AgN{O}_3\left(0.05{\text{mol kg}}^{-1}\right)|Ag\left(s\right)$

1. $-0.414\text{V}$
2. $0.828\text{V}$
3. $0.414\text{V}$
4. $0.0412\text{V}$

Q. $100\text{mL}$ of a $0.05\text{M}CuS{O}_4\text{aqueous}$ solution was electrolysed using inert electrodes by passing current till the pH of the resulting solution was 2. The solution after electrolysis was neutralised and then treated with excess $KI$ and the formed $I_2$ was titrated with $0.04\text{M}N{a}_2{S}_2{O}_3$. Calculate the volume of $N{a}_2{S}_2{O}_3$ required in $\text{mL}$.

1. $112.5\text{mL}$
2. $100\text{mL}$
3. $125\text{mL}$
4. None of these

Q. Standard reduction electrode potentials of three metals A, B and C are $+0.5V,-3.0V\&-1.2V$ respectively.
The decreasing order of reducing powers of these metals is:

1. $A>B>C$
2. $C>B>A$
3. $A>C>B$
4. $B>C>A$

Q. Polyacrylonitrile is an example of:

1. Addition polymer
2. Condensation polymer
3. Natural polymer
4. None of the above

Q. Consider the following reduction processes:

$Z{n}^{2+}+2e^{-}\to Zn\left(s\right);E^o=-0.76V$
$C{a}^{2+}+2e^{-}\to Ca\left(s\right);E^o=-2.87V$
$M{g}^{2+}+2e^{-}\to Mg\left(s\right);E^o=-2.36V$
$N{i}^{2+}+2e^{-}\to Ni\left(s\right);E^o=-0.25V$

The reducing power of the metals increases in the order:

1. $Ca<Zn<Mg<Ni$
2. $Ni<Zn<Mg<Ca$
3. $Zn<Mg<Ni<Ca$
4. $Ca<Mg<Zn<Ni$

Q.

Electrolysis of dilute NaCl solution produces Cl₂ at anode. This is because of

1. Overpotential of Cl₂

2. Overpotential of Na

3. Overpotential of H₂

4. Overpotential of O₂

Q. At equimolar concentration of $F{e}^{2+}\text{and}F{e}^{3+}$, what must $\left[A{g}^{+}\right]$ be so that the voltage of the galvanic cell made from $\left(A{g}^{+}/Ag\text{and}F{e}^{3+}/F{e}^{2+}\right)$ electrodes equals zero? The reaction is $F{e}^{2+}+A{g}^{+}\rightleftharpoons F{e}^{3+}+Ag$. (Given: $E_{A{g}^{+}/Ag}^0=0.799$ volt and $E_{F{e}^{+}/F{e}^{2+}}^0=0.771\text{volt.},{10}^{-0.47}=2.94)$ Give your answer upto two decimal only.

Q.

Explain faradays laws of electrolysis in details.

Q.

Electrolytes conduct electricity in their aqueous solution or molten state to undergo decomposition into ions.

1. True
2. False

Q. Heavy water is obtained by:

1. Boiling water
   
2. Fractional distillation of $H_{2}O$
   
3. Prolonged electrolysis of $H_{2}O$
   
4. Heating $H_2{O}_2$

Q. A silver electrode is immersed in saturated $A{g}_{2}S{O}_4\left(aq\right)$. The potential difference between silver and the standard hydrogen electrode is found to be $0.711V$.
Determine the $K_{sp}$ of $A{g}_{2}S{O}_4$ at ${25}^{o}C$.
Given:
$E_{A{g}^{+}/Ag}^0=0.799V{10}^{-1.5}\approx 0.031$

1. $K_{sp}=4.3\times {10}^{-4}$
2. $K_{sp}=2.77\times {10}^{-4}$
3. $K_{sp}=9.4\times {10}^{-6}$
4. $K_{sp}=1.54\times {10}^{-5}$

Q. For the galvanic cell at ${25}^{o}C$,
$Ag|AgCl\left(s\right),KCl\left(0.2M\right)||KBr\left(0.001M\right),AgBr\left(s\right)|Ag$

Which of the following(s) is/are true for the given cell?
Given:
$K_{sp}\left(AgCl\right)=2.8\times {10}^{-10}$
$K_{sp}\left(AgBr\right)=3.3\times {10}^{-13}$

1. The given cell reaction is non-spontaneous
2. The given cell reaction is spontaneous
3. At ${25}^{o}C,E_{cell}=-0.037V$
4. At ${25}^{o}C,E_{cell}=0.122V$

Q.

Predict the products of electrolysis in each of the following :

An aqueous solution of $AgN{O}_3$ with silver electrodes

An aqueous solution of $AgN{O}_3$ with platinum electrodes

A dilute solution of $H_{2}S{O}_4$ with platinum electrodes.

An aqueous solution of $CuC{l}_2$ with platinum electrodes.

Q.

State one relevant observation for: At the Anode when aqueous copper sulphate solution is electrolyzed during copper electrodes.

Q.

Predict the products of electrolysis in the following

1. Aqueous sodium chloride solution using platinum electrodes

2. Aqueous copper sulphate solution using platinum electrodes

Q. A galvanic cell is constructed by coupling a copper and a zinc electrode. If at $298K$:
$E_{C{u}^{2+}\left(aq\right)/Cu\left(s\right)}^{\circ }=+0.34V$
$E_{Z{n}^{2+}\left(aq\right)/Zn\left(s\right)}^{\circ }=-0.76V$

Which of the following is/are correct?

1. $Z{n}^{2+}$ has a higher oxidising power.
2. $C{u}^{2+}$ has a higher oxidising power.
3. $E_{Zn\left(s\right)/Z{n}^{2+}\left(aq\right)}^{\circ }=+0.76V$
4. $E_{Cu\left(s\right)/C{u}^{2+}\left(aq\right)}^{\circ }=+0.34V$

Q.

Explain why it is preferable to use several graphite electrodes as anodes instead of the single electrode during the above electrolysis.

Q. For a silver- magnesium voltaic cell, calculate the standard emf $\left(E_{cell}^0\right)$

$M{g}^{2+}+2e^{-}\to Mg\left(s\right);E^0=-2.37V$
$A{g}^{+}\left(aq\right)+e^{-}\to Ag\left(s\right);E^0=+0.80V$

1. $3.17V$
2. $-3.17V$
3. $1.57V$
4. $-1.57V$

Q.

Number of molecules in 14g of carbon monoxide is

1. $12.044\times {10}^{23}$

2. $6.022\times {10}^{23}$

3. $3.011\times {10}^{23}$

4. $1.5050\times {10}^{23}$

Q.

What happens during electrolysis of Brine?

Q. By which of the following methods, $H_2{O}_2$ can't be synthesised?

1. $\text{Addition of ice cold}{H}_{2}S{O}_4\text{on}Ba{O}_2$
2. $\text{Addition of ice cold}{H}_{2}S{O}_4\text{on}Pb{O}_2$
3. $\text{Aerial oxidation of 2-ethyl anthraquinol}$
4. $\text{Electrolysis of}(N{H}_4{)}_{2}S{O}_4\text{at a high current density}$

Q. Iron pipes lying under acidic soil are often attached to blocks of magnesium for protection from rusting. Magnesium offers protection to iron against corrosion because it
a) Prevents air from reaching the surface of iron
b) is more readily converted into positive ions
c) forms a corrosion resistive alloy with iron