Question

What is the effect of dilution on conductivity and molar conductivity of a solution?

Answer 1

Hint: In order to study the effect of dilution, we refer to the definitions of conductivity and molar conductivity of a solution and its properties.

Complete step by step answer:
Conductivity is a concept that comes into play in liquid state, in aqueous solutions, it is a measure of the ability of water to conduct an electric current. The electrons in the molecules are responsible for conduction of electricity. The more ions there are in the solution, the higher its conductivity. Also the more ions there are in solution, the stronger the electrolyte. This is why salts have more conductivity.

Conductivity is defined for the number of ions per ml (milliliter) of the solution. On dilution as volume of solution increases, thus number of ions per ml decreases and hence conductivity decreases.
Molar conductivity of a solution at a given concentration is the conductance of volume of solution containing one mole of electrolyte kept between two electrodes with an area of cross-section and distance of unit length. This concept is a measure of conductivity per the amount of electrolyte for a specific concentration of a solution, i.e. the ratio of substances in the solution.
Molar conductivity is defined for one mole of ions. When a solution is diluted, there are more ions and they have more space to move, i.e. ions are more far away from each other and mobility of ions increase which leads to increase in molar conductivity of the solution.
Hence when a solution is diluted, conductivity decreases and molar conductivity increases.

Note: In order to answer this type of questions the key is to have a good understanding on the concept of dilution and its effects. Dilution is the process of decreasing the concentration of a solute in a solution, by mixing it with more solvent like adding more water to a solution. To dilute a solution means to only add more solvent without the addition of more solute. Thus the volume of the solution increases.
The degree of conductivity is inversely proportional to dilution and molar conductivity is directly proportional to dilution.