Gibb's Free Energy

Q. The tendency of metals to liberate hydrogen gas from dilute acids decreases down the electrochemical series.

1. True
2. False

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. The Gibbs energy for the decomposition of $A{l}_2{O}_3$ at ${500}^{0}C$ is as follows:
$\frac{2}{3}A{l}_2{O}_3\to \frac{4}{3}Al+O_2$
${\Delta }_{rxn}G=+960kJmo{l}^{-1}$.The potential difference needed for the electrolytic reduction of aluminum oxide$\left(A{l}_2{O}_3\right)$ at ${500}^{o}C$ is:

1. 4.5 V
2. 3.0 V
3. 2.5 V
4. 5.0 V

Q.

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

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. 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 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. $d\left(\Delta G\right)=-\left(\Delta S_{\text{reaction}}\right).dT$ $\Delta G=\Delta H-T\Delta S$ $\Delta G=\Delta H+T{\left(\frac{d\left(\Delta G\right)}{dT}\right)}_P$
At $300\text{K},\Delta H$ for the reaction,
$Z{n}_{\left(S\right)}+2AgC{l}_{\left(S\right)}\to ZnC{l}_{2_{\left(aq\right)}}+2A{g}_{\left(S\right)}$
is $-218\text{kJ/mol}$ while the e.m.f of the cell is $1.015\text{V}$. ${\left(\frac{dE}{dT}\right)}_P$ of the cell is:

1. $-4.2\times {10}^{-4}{\text{VK}}^{-1}$
2. $-3.81\times {10}^{-4}{\text{VK}}^{-1}$
3. $0.11{\text{VK}}^{-1}$
4. $7.62\times {10}^{-4}{\text{VK}}^{-1}$

Q. Alkali metal(s) which can be produced by metal displacement method is (are):

1. Rb
2. K
3. Li
4. None of these