Question

An electrochemical cell is shown below
$$Pt,{H_2}\left( {1\,atm} \right)\left| {HCl\left( {0.1M} \right)} \right|$$     $$C{H_3}COOH\left. {\left( {0.1M} \right)} \right|{H_2}\left( {1\,atm} \right),$$       $$Pt$$
The $$EMF$$  of the cell will not be zero, because

A. $$EMF$$  depends on molarities of acids used
B. $$pH$$ of $$0.1\,M\,HCl$$   and $$0.1\,M\,{\text{C}}{{\text{H}}_3}COOH$$    is not same  
C. the temperature is constant
D. acids used in two compartments are different
Answer :   $$pH$$ of $$0.1\,M\,HCl$$   and $$0.1\,M\,{\text{C}}{{\text{H}}_3}COOH$$    is not same
Solution :
The $$EMF$$  of the cell will not be zero because concentration of $${H^ + }$$ $$ions$$  in two electrolytic solutions is different. Mean $$HCl$$  is strong acid where, acetic acid is weak acid and gives different $$pH.$$

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. $$Zn\left( s \right)$$
B. $$Cr\left( s \right)$$
C. $${H_2}\left( g \right)$$
D. $$F{e^{2 + }}\left( {aq} \right)$$
Releted Question 2

Faraday’s laws of electrolysis are related to the

A. atomic number of the reactants.
B. atomic number of the anion.
C. equivalent weight of the electrolyte.
D. speed of the cation.
Releted Question 3

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 :

A. $$Ag,Hg,Cu,Mg$$
B. $$Mg,Cu,Hg,Ag$$
C. $$Ag,Hg,Cu$$
D. $$Cu,Hg,Ag$$
Releted Question 4

The electric charge for electrode deposition of one gram equivalent of a substance is :

A. one ampere per second.
B. 96,500 coloumbs per second.
C. one ampere for one hour.
D. charge on one mole of electrons.

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