Question

Conductivity of metal decreases with temperature while conductivity of electrolytic conductors:
[A] Increases with temperature
[B] Decreases with temperature
[C] Remains the same
[D] Slightly increases with temperature

Answer 1

HINT: The ability of a species to carry charge and hence conduct electricity by the movement of the charge in the provided medium is conductivity. Remember that conductivity of metals is due to flow of electrons and that of electrolytic conductors is due to ions. Consider the factor of vibrational and kinetic energy to answer this.

COMPLETE STEP BY STEP SOLUTION:
-Firstly let’s discuss how the conductivity of metals varies with temperature then we will discuss the same for electrolytic conductors.
-We know that metals are good conductors of electricity due to the presence of free electrons. However, when we increase the temperature the vibrational motion of electrons increases and thus cause unwanted collisions which results in the increase of resistance in metals. Therefore the mobility of electrons decreases and causes decrease in conductivity.
-Now let us discuss electrolytic conductors. They are known as electrolytes in chemistry. The substance that dissociates into ions in aqueous medium is known as an electrolyte. These ions are the reason for the conductivity of such solutions.
-When we increase the temperature, the kinetic energy of the ions increases and they move faster i.e. they conduct their bearing charge faster and thus result in increased conductivity.
So, with increase in temperature, the conductivity of electrolytic conductors increases.
Therefore, the correct answer is option [A] Increases with temperature

NOTE: The electrolytes are divided into two groups depending on their strength namely strong and weak. There are factors other than temperature that affect the conductivity of an electrolyte. At a given constant temperature, the conductivity of solutions containing different electrolytes differs due to the concentration of the ions and difference in charge and size of the electrolytes when they dissociate into ions. Therefore, we needed to use the molar conductivity of each ion which is given as-
${{\lambda }_{m}}=\dfrac{k}{c}$
Where, ${{\lambda }_{m}}$is the molar conductance
K is the specific conductivity and
C is the concentration of the solution.