81.
Electrolysis of $$NaCl$$ solution with inert electrodes for certain period of time gave $$600\,c{m^3}$$ of $$1.0\,M\,NaOH$$ in the electrolytic cell. During the same period $$31.80\,g$$ of copper was deposited in a copper voltmeter in series with the electrolytic cell. What is the percent current efficiency in the electrolytic cell ? $$\left( {At.\,wt.\,{\text{of}}\,Cu = 63.6} \right)$$
83.
What will be the reduction potential for the following half-cell reaction at $$298\,K?$$
$$\left( {{\text{Given:}}\left[ {A{g^ + }} \right] = 0.1\,M\,{\text{and}}\,E_{{\text{cell}}}^ \circ = + 0.80\,V} \right)$$
84.
The emf of the cell $$Zn\left| {Z{n^{2 + }}\left( {0.01M} \right)} \right|\left| {F{e^{2 + }}\left( {0.001M} \right)} \right|Fe$$ at $$298 K$$ is $$0.2905$$ then the value of equilibrium constant for the cell reaction is
85.
During electrolysis of a solution of $$AgN{O_3},$$ 9650 coulombs of charge is passed through the solution. What will be the mass of silver deposited on the cathode?
86.
What will be the $$emf$$ of the following concentration cell at $${25^ \circ }C?$$
$$A{g_{\left( s \right)}}\left| {AgN{O_3}\left( {0.01\,M} \right)} \right|$$ $$\left| {AgN{O_3}\left( {0.05\,M} \right)} \right|A{g_{\left( s \right)}}$$
87.
$$1.08\,g$$ of pure silver was converted into silver nitrate and its solution was taken in a beaker. It was electrolysed using platinum cathode and silver anode. $$0.01$$ Faraday of electricity was passed using $$0.15\,volt$$ above the decomposition potential of silver. The silver content of the beaker after the above shall be
88.
On passing a current of $$1.0$$ ampere for $$16\,\min $$ and $$5\,\sec $$ through one litre solution of $$CuC{l_2},$$ all copper of the solution was deposited at cathode. The
strength of $$CuC{l_2}$$ solution was ( Molar mass of
$$Cu = 63.5;$$ Faraday constant $$ = 96500\,C\,mo{l^{ - 1}})$$
89.
Consider the following four electrodes :
$$\eqalign{
& P = C{u^{2 + }}\left( {0.0001\,M} \right)/Cu\left( s \right) \cr
& Q = C{u^{2 + }}\left( {0.1\,M} \right)/Cu\left( s \right) \cr
& R = C{u^{2 + }}\left( {0.01\,M} \right)/Cu\left( s \right) \cr
& S = C{u^{2 + }}\left( {0.001\,M} \right)/Cu\left( s \right) \cr} $$
If the standard reduction potential of $$C{u^{2 + }}/Cu$$ is $$ + 0.34\,V,$$ the reduction potentials in volts of the above electrodes follow the order.
$${E_{red}} = E_{red}^ \circ + \frac{{0.591}}{n}{\text{log}}\left[ {{M^{n + }}} \right]$$
Lower the concentration of $${{M^{n + }},}$$ lower is the reduction potential.
Hence order of reduction potential is : $$Q > R > S > P$$
90.
Which of the following statements is true?
A
When an aqueous solution of $$NaCl$$ is electrolysed, sodium metal is deposited at cathode.
B
There is no difference between specific conductivity and molar conductivity.
C
Silver nitrate solution can be stored in a copper container.
D
The addition of liquid bromine to iodide solution turns it violet.
Answer :
The addition of liquid bromine to iodide solution turns it violet.
When an aqueous solution of $$NaCl$$ is electrolysed, hydrogen is liberated at cathode. Specific conductivity and molar conductivity are different terms. Silver nitrate solution cannot be stored in a copper container as silver will get precipitated because of high reactivity of $$Cu$$ than $$Ag.$$
The addition of liquid bromine to iodide solution turns it violet.
$$\mathop {B{r_{2\left( l \right)}} + 2I_{\left( {aq} \right)}^ - }\limits_{{\text{Reddish - brown}}} \to 2Br_{\left( {aq} \right)}^ - + \mathop {{I_{2\left( l \right)}}}\limits_{{\text{Violet}}} $$