# Class 12 Chemistry Important Questions on Electrochemistry

## Electrochemistry Very Short Answer Type Questions- 1M

1. What is meant by standard electrode potential?
Answer: Standard electrode potential (E°) of a half cell is the potential difference when one electrode is dipped in molar solution of its ion at 298 K. If electrode is gaseous the pressure of gas must be one atmosphere. In IUPAC system, reduction potential are known as standard electrode potential.

2. Write Ohm’s law.
According to Ohm’s law, “It states that potential difference across the conductor is directly proportional to the current (I) flowing through it” i.e.,
Mathematically, it can be written as:
I ∝ V
V = IR (R = Resistance, unit = ohm, Q)

3.What is cell constant?
Answer: For a conductivity cell, the ratio of distance between two electrodes (l) and area of cross-section of electrode (A) is called as cell constant.
Cell constant = 1A or x = 1A
Unit of cell constant = cm-1

4. Write the unit of specific conductance.
ohm-1metre-1= Ω-1m-1 = Sm-1

## Electrochemistry Short Answer Type Questions- 2M

1. What is salt bridge ? Write its two functions.
‘U’ shaped tube filled with KCl or KNO3 in Agar – Agar solution or gelatin, is known as salt bridge. It connects the two half cell.

Functions:

1. It allows the flow of current by completing the circuit.
2. It maintains the electrical neutrality.

2.What is specific conductance? Give its unit.
Specific conductivity:
The reciprocal of resistivity is called specific conductivity. It is defined as the conductance between the opposite faces of one centimeter cube of a conductor. It is denoted by K (kappa).
Thus.
K = 1ρ (∵ ρ = RAl
K = 1R × 1A
where, R = Resistance, A = Cross – sectional area of electrodes and l = Length between the electrodes.
Unit = K = 1ohm × cmcm2 = ohm-1 cm-1
S.I. Unit Scm-1. or Ohm-1 cm-1.

3. What is equivalent conductance?
Equivalent conductance:
“Conductance of total ion produced by one gram equivalent of electrolyte in the solution is called equivalent conductance.” It is denoted by Λeq. 4.What is molar conductance?
Molar Conductivity:
The molar conductivity of a solution at definite concentration of (or dilution) and temperature is the conductivity of that volume which contains one mole of the solute and is placed between two parallel electrodes 1 cm apart and having sufficient area to hold whole of the solution. It is denoted by Λm.
Mathematically,
Λ m=k × V .. (1)
Where, V is the volume in ml in which one gram mole of substance is dissolved.
If M is molarity or m moles are dissolved in 1000 ml. Write difference between Metallic conduction and Electrolytic conduction.

What are the difference between emf (Cell potential) and potential difference:

Differentiate between Electrochemical cell (Galvanic cell) and Electrolytic cell.