Question

Mention the factors that affect the rate of a chemical reaction.

Comments

The factors that affect the rate of a chemical reaction are:-

1. Concentration:- 

On increasing concentration of reactants, the probability of collisions of molecules increases, hence rate of reaction increases.  

2. Temperature:- 

On increasing temperature, the kinetic energy of molecules increases, hence, the number of collision increases. Therefore, the rate of reaction also increases. 

3. Pressure:- 

On increasing pressure, the molecules of gases come closer to each other. As a result their collisions increase and hence rate of reaction increases. 

4. Surface area of Reactants:- 

On increasing surface area of reactants, the rate of reaction increases. For example, the powdered metals react faster than the metals in a lump. 

5. Nature of Reactants:- 

If the reactants are ionic in nature, than the rate of reaction is faster than those in which reactants are molecular in nature. 

Answer 1

The factors that affect the rate of a chemical reaction are as follows:

1. Nature of the reactants: Nature or reactivity of reactants influences the rate of a chemical reaction.
   E.g. Al is more reactive than Zn. Therefore, the rate of reaction of Al with hydrochloric acid is higher than that of Zn.
2. Size of the particles of the reactants: Smaller the size of the reactant particles, higher is the rate of the reaction.
   E.g. When HCl is added to pieces of Shahabad tile, the CO₂ effervescence is formed slowly. However, when HCl is added to Shahabad powder, the CO₂ effervescence is formed at a faster rate.
3. Concentration of the reactants: The rate of a chemical reaction increases with increase in the concentration of the reactants.
   E.g. Dilute HCl reacts slowly with calcium carbonate, CaCO₃ whereas concentrated HCl reacts rapidly with CaCO₃.
4. Temperature of the reaction: Higher the temperature, faster is the rate of a chemical reaction.
   E.g. The temperature in the refrigerator is low. So, the rate of decomposition of perishable foodstuffs is low and it remains fresh for a longer time.
5. Catalyst: Presence of catalyst increases the rate of a chemical reaction.
   E.g. The decomposition of hydrogen peroxide into water and oxygen takes place slowly at room temperature. However, the same reaction occurs at a faster rate on adding manganese dioxide (MnO₂) powder in it.