Define Conductivity , Molar conductivity and Equivalent conductivity In Detail.
Class 12th (chemistry)
Answers
Electrical conductance :- Reciprocal of resistance of a conductor.
unit :- ohm^- , mho , Siemens .
Molar conductance :- The conductance of that amount of solution which contains 1 mole of electrolyte is called molar conductance .
molar conductance =( K× 1000)/M where m is molarity.
Equivalent conductance :- It is the conductance that volume of solution which contains 1 equvalent of electrolytes.
equvalent conductance = ( K ×10000)/N where N is Normality.
Relation between Molar and equvalent conductance .
=>eq. conductance = Molar conductance / n
where n is factor of salt .
Answer:
Conductivity of a solution is defined as the conductance of a solution of 1 cm in length and area of cross-section 1 sq. cm. The inverse of resistivity is called conductivity or specific conductance. It is represented by the symbolκ. If ρ is resistivity, then we can write:
The conductivity of a solution at any given concentration is the conductance (G) of one unit volume of solution kept between two platinum electrodes with the unit area of cross-section and at a distance of unit length.
i.e.,
(Since a = 1, l = 1)
Conductivity always decreases with a decrease in concentration, both for weak and strong electrolytes. This is because the number of ions per unit volume that carry the current in a solution decreases with a decrease in concentration.
Molar conductivity:
Molar conductivity of a solution at a given concentration is the conductance of volume V of a solution containing 1 mole of the electrolyte kept between two electrodes with the area of cross-section A and distance of unit length.
Now, l = 1 and A = V (volume containing 1 mole of the electrolyte).
Molar conductivity increases with a decrease in concentration. This is because the total volume V of the solution containing one mole of the electrolyte increases on dilution.