Electrochemical Cells, Galvanic Cells

Q. Calculate the approximate number of unit cells present in 1g of gold . Gold crystallizes in the fcc lattice ?

Q. The conductivity of $0.1MNaCl$ is $3\times {10}^{-3}Sc{m}^{-1}$ and its resistance in an electrolytic cell is $500ohm$. Resistance of $\frac{1}{20}MCuS{O}_4$ solution measured in the same cell at the same temperature is found to be $70ohm$. The molar conductivity of the given $CuS{O}_4$ solution is ?

1. $428Sc{m}^{2}mo{l}^{-1}$
   
2. $120.2Sc{m}^{2}mo{l}^{-1}$
   
3. $20.5Sc{m}^{2}mo{l}^{-1}$
   
4. $12.50Sc{m}^{2}mo{l}^{-1}$
   

Q.

What is the solubility of $\mathrm{Ca}{\left(\mathrm{OH}\right)}_2$ water? (Given the solubility product of $\mathrm{Ca}{\left(\mathrm{OH}\right)}_2$ water$=5.5\times {10}^{-6}$)

1. $1.11\times {10}^{-6}$

2. $1.77\times {10}^{-6}$

3. $1.77\times {10}^{-2}$

4. $1.11\times {10}^{-2}$

Q. Tetragonal crystal system has which of the following unit cell dimensions:

1. $a=b=c$ and $\alpha =\beta =\gamma ={90}^{\circ }$
2. $a=b\ne c$ and $\alpha =\beta ={90}^{\circ },\gamma ={120}^{\circ }$
3. $a\ne b\ne c$ and $\alpha =\beta =\gamma ={90}^{\circ }$
4. $a=b\ne c$ and $\alpha =\beta =\gamma ={90}^{\circ }$

Q.

What is the work done by an electrochemical cell equal to?

Q. Why the electrical discharge through the gases could be observed only at very low pressure and very high voltage

Q.

In which of the following pair, most efficient packing is present?

1. hcp and bcc

2. hcp and ccp

3. bcc and ccp

4. bcc and simple cubic cell

Q.

What is the chemical composition of rust?

Q. Which of the following crystal is represented by $a\ne b\ne c\text{and}\alpha =\beta =\gamma ={90}^{\circ }$?
[0.77 Mark]

1. Tetragonal
2. Cubic
3. Orthorhombic
4. Trigonal

Q. For the electrochemical cell:
$Mg\left(s\right)|M{g}^{2+}(aq,1M)||C{u}^{2+}\left)\right(aq,1M\left)|Cu\right(s)$ the standard emf of the cell is 2.70 V at 300 K. When the concentration of $M{g}^{2+}$ is changed to 'x' M, the cell potential changes to 2.67 V at 300 K. The value of 'x' is.

(given, $\frac{F}{R}=11500K{V}^{-1}$, where $F$ is the Faraday constant and $R$ is the gas constant, ln(10)=2.30)

Q.

Differentiate between primary cell and secondary cell

Q.

Using the standard electrode potentials given in Table 3.1, predict if the reaction between the following is feasible:

(i) Fe³⁺(aq) and I⁻(aq)

(ii) Ag⁺ (aq) and Cu(s)

(iii) Fe³⁺ (aq) and Br⁻ (aq)

(iv) Ag(s) and Fe³⁺ (aq)

(v) Br₂ (aq) and Fe²⁺ (aq).

Q. Which primitive unit cell has all the edge lengths equal i.e. $a=b=c$ and all the axial angles equal to each other but not equal to ${90}^{\circ }$ i.e. $\alpha =\beta =\gamma \ne {90}^{\circ }$?

1. Monoclinic
2. Triclinic
3. Trigonal
4. Hexagonal

Q. In this electrochemical cell the direction of current is .

1. zinc to copper rod
2. copper to zinc rod
3. anode to cathode

Q. In a galvanic cell, the salt bridge

1. Does not participate chemically in the cell reaction
2. Stops the diffusion of ions from one electrode to another
3. Minimize the liquid junction potential
4. Ensures mixing of the two electrolytic solution

Q.

Does the pressure affect the cell potential?

Q.

How are zener diodes made?

Q. . Calculate E°cell and ∆rG° for the following reaction at 25°C. A2+(aq) + B+(aq) → A3+(aq) + B(s) [Given KC = 1010, 1F = 96500 C, R = 8.314 JK–1 mol–1]

Q.

Describe the cathodic protection of metals from corrosion.

Q. Explain the effect of concentration on molar conductivity of weak and strong electrolytes

Q.

Are lithium batteries AC or DC?

Q. In a galvanic cell, the correct statement will be:

1. Current flows from the anode to the cathode
2. If $E_{cell}<0$, it is a spontaneous reaction
3. Cathode is the positive terminal
4. Anode is the positive terminal

Q.

Four metals A, B, C and D have standard reduction potential of -3.08V, -1.56V, -0.30V and 0.65V respectively. The metal which is most easily reduced is :

1. D

2. B

3. C

4. A

Q.

Car batteries are an example of secondary cells.

1. True
2. False

Q.

Primary cells ……. (cannot/can) be recharged as chemical reactions within the cells are irreversible.

Q.

For cell reaction, $Zn+C{u}^{2+}\to Z{n}^{2+}+Cu,$ cell representation is

1. 
   

2. 
   

3. 
   

4. 
   

Q.

What is the role of graphite rod in the electrometallurgy of aluminium?

Q. The molar conductivity of $0.04\text{M}$ solution of $MgC{l}_2$​ is $200{\text{S cm}}^3{\text{mol}}^{-1}$ at $298\text{K}$. A cell with electrodes that are $2.0{\text{cm}}^2$ in surface area and $0.50\text{cm}$ apart is filled with $MgC{l}_2$​ solution. How much current will flow when the potential difference between the two electrodes is $5.0\text{V}$?

1. $156.25\text{A}$
2. $0.16\text{A}$
3. $160\text{A}$
4. None of these

Q. Which of the following reaction is correct for a given electrochemical cell at ${25}^{\circ }C$ ?
$Pt\left(s\right)|B{r}^{-}\left(aq\right)|B{r}_2\left(g\right)||C{l}_2\left(g\right)|C{l}^{-}\left(aq\right)|Pt\left(s\right)$

1. $2B{r}^{-}\left(aq\right)+C{l}_2\left(g\right)\to 2C{l}^{-}\left(aq\right)+B{r}_2\left(g\right)$
2. $B{r}_2\left(g\right)+2C{l}^{-}\left(aq\right)\to 2B{r}^{-}\left(aq\right)+C{l}_2\left(g\right)$
3. $B{r}_2\left(g\right)+C{l}_2\left(g\right)\to 2B{r}^{-}\left(aq\right)+2C{l}^{-}\left(aq\right)$
4. $2B{r}^{-}\left(aq\right)+2C{l}^{-}\left(aq\right)\to B{r}_2\left(g\right)+C{l}_2\left(g\right)$

Q. $1.0N$ solution of a salt surrounding two platinum electrodes of $2.1cm$ apart and $4.2c{m}^2$ in area was found to offer a resistance of $50ohm$. Calculate the equivalent conductivity of the solution.

1. ${\Lambda }_{eq}={10}^{-5}oh{m}^{-1}c{m}^{2}e{q}^{-1}$
2. ${\Lambda }_{eq}=0.01oh{m}^{-1}c{m}^{2}e{q}^{-1}$
3. ${\Lambda }_{eq}=100oh{m}^{-1}c{m}^{2}e{q}^{-1}$
4. ${\Lambda }_{eq}=10oh{m}^{-1}c{m}^{2}e{q}^{-1}$