Electrochemistry 2

Question 1

resistivity aka

Answer 1

specific resistance

Question 2

resistivity

Answer 2

, the resistivity
for a substance is its resistance when it is one metre long and its area
of cross section is one m2.

Question 3

conductance

Answer 3

The inverse of resistance, R, is called conductance, G,

Question 4

Conductivity

Answer 4

Conductivity of a
material in S m–1 is its conductance when it is 1 m long and its area
of cross section is 1 m2.

Question 5

1 S cm–1 =

Answer 5

100 S m–1.

Question 6

factors affecting conductivity of the material

Answer 6

• nature of the material
• temperature
• pressure

Question 7

On what basis are materials classified into conductors, semi-conductors and insulators?

Answer 7

• Materials are classified into conductors, insulators and
  semiconductors depending on the magnitude of their conductivity.
• Metals
  and their alloys have very large conductivity and are known as conductors.
• Certain non-metals like carbon-black, graphite and some organic
  polymers* are also electronically conducting.
• Substances like glass,
  ceramics, etc., having very low conductivity are known as insulators.
• Substances like silicon, doped silicon and gallium arsenide having
  conductivity between conductors and insulators are called
  semiconductors and are important electronic materials.
• Certain materials
  called superconductors by definition have zero resistivity or infinite
  conductivity.

Question 8

The electronic
conductance depends on

Answer 8

(i) the nature and structure of the metal
(ii) the number of valence electrons per atom
(iii) temperature (it decreases with increase of temperature).

Question 9

Electrical conductance through metals is called metallic or electronic
conductance and is due to

Answer 9

the movement of electrons.

Question 10

ionic conductance

Answer 10

The
conductance of electricity by ions present in the solutions is called
electrolytic or ionic conductance.

Question 11

The conductivity of electrolytic (ionic)
solutions depends on:

Answer 11

(i) the nature of the electrolyte added
(ii) size of the ions produced and their solvation
(iii) the nature of the solvent and its viscosity
(iv) concentration of the electrolyte
(v) temperature (it increases with the increase of temperature)