$$1.0\,L$$ each of a buffer containing $$1\,mole$$ $$N{H_3}$$ and
$$1\,mole$$ of $$NH_4^ + $$ were placed in the cathodic and anodic half-cells and $$965\,C$$ of electricity was passed. If anodic and cathodic half cells reactions involve oxidation and reduction of water only as $$2{H_2}O \to 4{H^ + } + {O_2} - 4{e^ - };$$ $$2{H_2}O + 2{e^ - } \to {H_2} + 2O{H^ - }$$
Then $$pH$$ of
A.
cathodic solution will increase
B.
anodic solution will decrease
C.
both the solutions will remain practically constant
D.
both the solutions will increase
Answer :
both the solutions will remain practically constant
Solution :
Due to buffer action the pH will remain practically constant.
Releted MCQ Question on Physical Chemistry >> Electrochemistry
Releted Question 1
The standard reduction potentials at $$298 K$$ for the following half reactions are given against each
$$\eqalign{
& Z{n^{2 + }}\left( {aq} \right) + 2e \rightleftharpoons Zn\left( s \right)\,\,\,\,\,\,\,\,\, - 0.762 \cr
& C{r^{3 + }}\left( {aq} \right) + 2e \rightleftharpoons Cr\left( s \right)\,\,\,\,\,\,\,\,\, - 0.740 \cr
& 2{H^ + }\left( {aq} \right) + 2e \rightleftharpoons {H_2}\left( g \right)\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,0.000 \cr
& F{e^{3 + }}\left( {aq} \right) + 2e \rightleftharpoons F{e^{2 + }}\left( {aq} \right)\,\,\,\,\,\,\,\,0.770 \cr} $$
which is the strongest reducing agent ?
A solution containing one mole per litre of each $$Cu{\left( {N{O_3}} \right)_2};AgN{O_3};H{g_2}{\left( {N{O_3}} \right)_2};$$ is being electrolysed by using inert electrodes. The values of standard electrode potentials in volts (reduction potentials) are :
$$\eqalign{
& Ag/A{g^ + } = + 0.80,\,\,2Hg/H{g_2}^{ + + } = + 0.79 \cr
& Cu/C{u^{ + + }} = + 0.34,\,Mg/M{g^{ + + }} = - 2.37 \cr} $$
With increasing voltage, the sequence of deposition of metals on the cathode will be :