Gibb's Free Energy

Q. Given that the standard potentials ($E^0$) of $C{u}^{2+}/Cu\text{and}C{u}^{+}/Cu$ are $0.34V$ and $0.522V$ respectively, the $E^0$ of $C{u}^{2+}/C{u}^{+}$ is-
(JEE MAIN 2020)

1. $-0.182V$
2. $+0.158V$
3. $0.182V$
4. $-0.158V$

Q. What is the $\Delta G^{\circ }$ for the following reaction?
$C{u}_{\left(aq\right)}^{2+}+2A{g}_{\left(s\right)}\to C{u}_{\left(s\right)}+2A{g}_{\left(aq\right)}^{+}$
Given:$E_{C{u}^{2+}/Cu}^0=0.34V,E_{Ag/A{g}^{+}}^0=-0.8V$

1. -89 kJ
2. 89 kJ
3. -44.5 kJ
4. 44.5 kJ

Q. The standard electrode potential $\left(E^{\circ }\right)$ for Daniel cell is + 1. 1 V. Calculate the $\Delta G^{\circ }$ for the reaction $Zn\left(s\right)+C{u}^{2+}\left(aq\right)⟶Z{n}^{2+}\left(aq\right)+Cu\left(s\right)$
$(1F=96500Cmo{l}^{-1}).$

Q.

Identify the following equation

$\mathrm{Fe}+\mathrm{S}\to \mathrm{FeS}$

Q.

Give examples of slow reaction

Q. Assume a cell with the following reaction

$C{u}_{\left(s\right)}+2A{g}^{+}(1\times {10}^{-3}M)\to C{u}^{2+}\left(0.250M\right)+2Ag\left(s\right)$

$E_{cell}^0=2.97V$

$E_{cell}$ for the above reaction is ____V. (Nearest integer)
[Given : $log2.=0.3979,T=298K$]

Q. Crystal field stabilization energy for ${\left[Co{F}_6\right]}^{-3}$ is :
[ P is pairing energy ]

1. $0.6+P$
2. $-0.4+P$
3. $1.2+2P$
4. $2.4+4P$

Q. The carbon reduction method is mainly applicable for the extraction of how many of the following metals?
$Sn,Al,Cr,Mn,Pb,Ca,Na,Zn$

Q. Calculate the reduction potential for the given half cells at ${25}^{o}C$.
$Pt\left(s\right)|F{e}^{2+}(aq,0.1M),F{e}^{3+}(aq,0.01M);E_{F{e}^{3+}/F{e}^{2+}}^0=+0.77V$

1. $E_{F{e}^{3+}/F{e}^{2+}}=0.77V$
2. $E_{F{e}^{3+}/F{e}^{2+}}=-0.83V$
3. $E_{F{e}^{3+}/F{e}^{2+}}=0.711V$
4. $E_{F{e}^{3+}/F{e}^{2+}}=0.83V$

Q. The temperature coefficient of emf of a cell designed as $Zn|\underset{\left(1M\right)}{Z{n}^{2+}}||\underset{\left(0.1M\right)}{C{u}^{2+}}|Cu$ is $-1.4\times {10}^{-4}V$ per degree. Change in entropy for the reaction $Zn+\underset{0.1M}{C{u}^{2+}}\rightleftharpoons \underset{1M}{Z{n}^{2+}}+Cu$ at ${27}^{\circ }C$ is:$(E_{cell}^{\circ }=1.1V)$

1. 14 J
2. 27 J
3. -14 J
4. -27 J

Q. In the process of extraction of gold, the following reaction takes places: $\text{Roasted gold ore}+C{N}^{-}+O_2+2H_{2}O\to \left[X\right]+O{H}^{-}$
$\left[X\right]+Zn\to \left[Y\right]+Au$
Identify the compounds [X] and [Y].

1. $\left[X\right]=\left[Au\right(CN{)}_2{]}^{-},\left[Y\right]=\left[Zn\right(CN{)}_4{]}^{2-}$
2. $\left[X\right]=\left[Au\right(CN{)}_4{]}^{3-},\left[Y\right]=\left[Zn\right(CN{)}_4{]}^{2-}$
3. $\left[X\right]=\left[Au\right(CN{)}_2{]}^{-},\left[Y\right]=\left[Zn\right(CN{)}_6{]}^{4-}$
4. $\left[X\right]=\left[Au\right(CN{)}_4],[Y]=[Zn(CN{)}_6{]}^{2-}$

Q. The $E^{\circ }$ at ${25}^{\circ }C$ for the following reaction is $0.22V$. Calculate the equilibrium constant at ${25}^{\circ }C$:
$H_2\left(g\right)+2AgCl\left(s\right)\to 2Ag\left(s\right)+2HCl\left(aq\right)$

1. $5.2\times {10}^8$
2. $5.2\times {10}^6$
3. $5.2\times {10}^3$
4. $2.8\times {10}^7$

Q. The EMF of the cell $M|M^{n^{+}}\left(0.02\text{M}\right)||H^{+}\left(1\text{M}\right)|H_2\text{(g)}\left(1\text{atm}\right),Pt$ at ${25}^{\circ }\text{C}$ is $0.81\text{V}$. Calculate the valency of the metal if the standard oxidation potential of the metal is $0.76\text{V}$.
(Given, $\log 4=0.6$)

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

Q. Extraction of Ag or Au is done the cyanide process and refined form of the metals are obtained at the end. Some processes are mentioned below.

(I) Leaching
(II) Reduction
(III) Complexation

Out of the given processes the one(s) which are used in the cyanide process is/are

1. Only (I) and (III)
2. (I), (II) and (III)
3. Only (I) and (III)
4. Only (II) and (III)

Q.

Hydrogen peroxide decomposes into water and oxygen. The uncatalyzed reaction has activation energy of $86\mathrm{kJ}/\mathrm{mol}$. The ${\mathrm{E}}_{\mathrm{a}}$ value in the presence of acetanilide is $112\mathrm{kJ}/\mathrm{mol}$ and in the presence of ${\mathrm{MnO}}_2$ it is $49\mathrm{kJ}/\mathrm{mol}$. What conclusion can you draw from the above observations?

Q.

The metal extracted by leaching with cyanide is:

1. $\mathrm{Cu}$

2. $\mathrm{Mg}$

3. $\mathrm{Na}$

4. $\mathrm{Ag}$

Q. $Pt\left(s\right)\mid M\left(s\right)\mid M^{3+}(aq,0.002mol{L}^{-1})\parallel A{g}^{+}(aq,0.01mol{L}^{-1})\mid Ag\left(s\right)$

The emf of the given cell is found to be $0.42V$ at ${25}^{\circ }C$. Calculate the standard potential of the half reaction.
$M^{3+}\left(aq\right)+3e^{-}\to M\left(s\right)$
Given:
${E^0}_{A{g}^{+}/Ag}=0.80V$

1. $-0.041V$
2. $-0.723V$
3. $0.315V$
4. $0.124V$

Q.

For a thermodynamically spontaneous process the change in free energy is __.

Q. In aqueous solution, ${Cr}^{2+}$ is a stronger reducing agent than ${Fe}^{2+}$. This is because:

1. ${Cr}^{2+}$ ion is more stable than ${Fe}^{2+}$.
2. ${Cr}^{3+}$ ion with $d^3$ configuration has favourable crystal field stabilisation energy.
3. ${Cr}^{3+}$ has half-filled configuration and hence more stable
4. ${Fe}^{3+}$ in aqueous solution is more stable than ${Cr}^{3+}$.
5. ${Fe}^{2+}$ ion with $d^6$ configuration has favourable crystal field stabilisation energy.

Q. The solubility product of $AgBr\left(s\right)$ is $5\times {10}^{-13}$ at $298K$. If the standard reduction potential of the half cell $E_{B{r}^{-}|AgBr|Ag}^0$ is $0.07V$.
Find the value of the $E_{A{g}^{+}/Ag}^0$

1. 0.8 V
2. 1.2 V
3. 0.34 V
4. 1.4 V

Q. The standard potential is given below, of the following at ${25}^{\circ }C$.
$Mn{O}_2\to M{n}^{3+}{E}^{\circ }=0.95V$
$M{n}^{+3}\to M{n}^{2+}{E}^{\circ }=1.51V$
The standard potential of $Mn{O}_2\to M{n}^{2+}$ is :

1. $-0.56V$
2. $-2.46V$
3. $-1.23V$
4. $1.23V$

Q. A galvanic cell is formed by immersing $Ag\left(s\right)$ in $AgN{O}_3(aq,0.1M)$ and $Cu\left(s\right)$ in $CuS{O}_4(aq,4M)$ at $298\text{K}$
Calculate the EMF of the cell.
Given:
$E_{A{g}^{+}/Ag}^0=0.80V$
$E_{C{u}^{2+}/Cu}^0=0.34V$

1. $E_{cell}=0.301V$
2. $E_{cell}=0.383V$
3. $E_{cell}=0.45V$
4. $E_{cell}=1.04V$

Q.

The $E^{\circ }$ in the given diagram is

1. 0.52 V

2. 0.61 V

3. 0.74 V

4. 0.83 V

Q.

Write the chemical reactions involved in the extraction of gold by cyanide process. Also give the role of zinc in the extraction.

Q.

$\mathrm{Pb}\mathrm{and}\mathrm{Sn}$ are extracted respectively from their chief ore by

1. (a) Carbon reduction and self reduction

2. (b) Self reduction and carbon reduction

3. (c) Electrolysis and self reduction

4. (d) Self reduction and electrolysis

Q. For the reaction, $A{g}_{\left(\text{aq}\right)}^{+}+C{l}_{\left(\text{aq}\right)}^{-}\rightleftharpoons AgC{l}_{\left(\text{s}\right)}$
Given:
$\begin{array}{cc}\text{Species}& \Delta G_f^{\circ }\left(\text{kJ/mol}\right)\\ A{g}_{\left(\text{aq}\right)}^{+}& +77\\ C{l}_{\left(\text{aq}\right)}^{-}& -129\\ AgC{l}_{\left(\text{s}\right)}& -109\end{array}$
Calculate $E_{\text{cell}}^{\circ }$ at $298\text{K}$.
Also find the solubility product of $AgCl$.

1. $0.59\text{V}$ and ${\text{K}}_{\text{sp}}={10}^{-10}$
2. $0.79\text{V}$ and ${\text{K}}_{\text{sp}}=3\times {10}^{-5}$
3. $0.36\text{V}$ and ${\text{K}}_{\text{sp}}={10}^{-14}$
4. $-0.59\text{V}$ and ${\text{K}}_{\text{sp}}={10}^{-10}$

Q. For the reaction, $A{g}_{\left(\text{aq}\right)}^{+}+C{l}_{\left(\text{aq}\right)}^{-}\rightleftharpoons AgC{l}_{\left(\text{s}\right)}$
Given:
$\begin{array}{cc}\text{Species}& \Delta G_f^{\circ }\left(\text{kJ/mol}\right)\\ A{g}_{\left(\text{aq}\right)}^{+}& +77\\ C{l}_{\left(\text{aq}\right)}^{-}& -129\\ AgC{l}_{\left(\text{s}\right)}& -109\end{array}$
Calculate $E_{\text{cell}}^{\circ }$ at $298\text{K}$.
Also find the solubility product of $AgCl$.

1. $0.59\text{V}$ and ${\text{K}}_{\text{sp}}={10}^{-10}$
2. $0.79\text{V}$ and ${\text{K}}_{\text{sp}}=3\times {10}^{-5}$
3. $0.36\text{V}$ and ${\text{K}}_{\text{sp}}={10}^{-14}$
4. $-0.59\text{V}$ and ${\text{K}}_{\text{sp}}={10}^{-10}$

Q. The change in entropy for the following transformations is respectively
(i) $S{O}_{2}C{1}_2\left(g\right)\stackrel{\Delta }{\to }S{O}_2\left(g\right)+C{1}_2\left(g\right)$
(ii) $nC{H}_2=C{H}_2\stackrel{Catalyst}{\to }[-C{H}_2-C{H}_2-{]}_{n\left(s\right)}$
(iii) $I_2\left(s\right)\underset{1atm}{\overset{\Delta }{\to }}{I}_2\left(v\right)$
(iv) Adiabatic reversible expansion of an ideal gas

1. +, -, 0, 0
2. +, -, 0, +
3. -, +, +, 0
4. +, -, +, 0

Q. The crystal fied stabilization energy $\left(CFSE\right)$ of $\left[Fe\right(H_{2}O{)}_6]C{l}_2$ and $K_2\left[NiC{l}_4\right]$, respectively, are:

1. $-0.6{△}_o$ and $-0.8{△}_t$
2. $-0.4{△}_o$ and $-0.8{△}_t$
3. $-2.4{△}_o$ and $-1.2{△}_t$
4. $-0.4{△}_o$ and $-1.2{△}_t$

Q. Calculate the concentration of electrolyte ($C_1$) at anode for the given cell:

$Ag\left(s\right)|AgN{O}_3(aq,C_{1}M)||AgN{O}_3(aq,C_2=0.2M)|Ag\left(s\right)$

The emf of the cell is $0.8V$

Take
$Antilog\left(13.5\right)=3.16\times {10}^{13}$

1. $C_1=3.16\times {10}^{-13}$
2. $C_1=3.16\times {10}^{13}$
3. $C_1=6.32\times {10}^{13}$
4. $C_1=0.63\times {10}^{-14}$