Active Mass and Rate of Reaction:

The rate of a chemical reaction depends on several factors such as temperature, concentration, pressure, and the presence of a catalyst. The active mass of a substance is another important factor that affects the rate of reaction. In this context, active mass refers to the concentration of the substance in a solution or a gaseous mixture, which is available to participate in the reaction.

Factors affecting the Active Mass:

The active mass of a substance can be affected by several factors such as:

1. Concentration: The higher the concentration of a substance, the higher its active mass, and the faster the reaction rate.

2. Pressure: In the case of gases, the active mass is directly proportional to the partial pressure of the gas. Therefore, increasing the pressure of a gas mixture can increase the active mass of the reactant gases and hence the reaction rate.

3. Surface Area: In the case of solid reactants, the active mass is related to the surface area of the solid. Therefore, increasing the surface area of the solid can increase the active mass of the solid and hence the reaction rate.

4. Temperature: Increasing the temperature of a reaction mixture can increase the reaction rate by increasing the active mass of the reactants.

Why Active Mass Matters:

The active mass of a substance is important because it is the concentration of the substance that is available to participate in the reaction. For example, consider the following reaction:

A + B → C

If the concentration of A is much higher than B, then the reaction rate will be limited by the concentration of B, which is the limiting reactant. Therefore, the active mass of B is more important in determining the reaction rate than the active mass of A.

Conclusion:

In conclusion, the rate of a chemical reaction depends on several factors, including the active mass of the reactants. The active mass is the concentration of the substance that is available to participate in the reaction. Therefore, increasing the active mass of a substance can increase the reaction rate.