Question

Which of the following is the correct representation of the given cell reaction?
$Zn+{{H}_{2}}S{{O}_{4}}\to ZnS{{O}_{4}}+{{H}_{2}}$

(A)- $Zn|Z{{n}^{2+}}||{{H}^{+}}|{{H}_{2}}$
(B)- $Zn|Z{{n}^{2+}}||{{H}^{+}},{{H}_{2}}|Pt$
(C)- $Zn|Z{{n}^{2+}}||{{H}_{2}}S{{O}_{4}}|Zn$
(D)- $Zn|{{H}_{2}}S{{O}_{4}}||ZnS{{O}_{4}}|{{H}_{2}}$

Answer 1

Cell representation, also known as cell notation or line notation in electrochemistry is a shorthand way of expressing a certain reaction in an electrochemical cell. The half cell, i.e anode, and cathode are separated by two bars or slashes representing a salt bridge, with the anode on the left and cathode on the right side.

Complete step by step answer:
-The anode is the electrode in an electrochemical cell where the oxidation, that is, loss of electrons occurs.
- The cathode is the electrode in an electrochemical cell where the reduction that is, gain of electrons occurs.
-In the reaction $Zn + {{H}_{2}}S{{O}_{4}}\to ZnS{{O}_{4}} + {{H}_{2}}$, we can see that the oxidation state of Zn is changing from 0 to +2 which means that Zn is undergoing oxidation. The oxidation state ${{H}^{+}}$ is changing from +1 to 0, which means that Hydrogen is undergoing reduction.
-In electrochemical cells, the oxidation reaction takes place at the anode and the reduction reaction takes place at the cathode.

-In the cell notation, the following conventions are used-
(i) The electrode with higher oxidation potential (negative electrode or anode) is written on the left side.
(ii) The electrode material is written first and then its electrolyte.
(iii) The electrode with lower oxidation potential (positive electrode or cathode) is written on the right side.
(iv) The electrolyte is written first followed by the electrode material.
(v) A single vertical line is drawn between the anode and cathode elements which represent the direct contact but the separation of the two phases.
(vi) The double vertical line is drawn between two solutions which indicate that the contact between the electrodes is through a porous pot or a salt bridge.
(vii) The concentration or activity of the solutions at the two electrodes is written in brackets.
(viii) In the case of a gas electrode, inert metal conductors like platinum are used to establish electrical contact, hence it is also incorporated in the convention.

So, following the above conventions for writing the representation of the cell -
$Zn|Z{{n}^{2+}}||{{H}^{+}},{{H}_{2}}|Pt$
So, the correct answer is “Option B”.

Note: There are two types of electrochemical cells, the first one is a galvanic cell, also known as voltaic cell and the second one is an electrolyte cell. A galvanic cell induces a spontaneous reaction to create a flow of charges or electricity. For example, non-rechargeable batteries are examples of galvanic cells. An electrolytic cell is the one that requires an outside electrical source to drive the non-spontaneous redox reaction. For example, rechargeable batteries.