What is the active mass of $5\text{g}$$\mathrm{CaO}$?

Active mass

• The number of g mol per liter is known as active mass.
• It is the mass that is taking part in a reaction.
• It's also known as molarity or molar concentration.
• It is the effective concentration of a material.

Active mass of $5\text{g}$ $\mathrm{CaO}$:

• In the case of solid the mass is always constant.
• So, it is taken as unity.
• As $\mathrm{CaO}$ is a solid Hence its active mass will be one.

The calculated active mass of $\mathrm{CaO}$ is $1\text{g}$ because, in the case of solids, it is equal to $1$.