RATE OF CHEMICAL REACTIONS
RATE OF CHEMICAL REACTION
During a chemical reaction, reactants are converted into products. The rate of chemical reaction tell us how fast a chemical reaction is taking place by indicating how much of a reactant is consumed, or how much of a product is produced in a given time. Therefore,
SLOW AND FAST CHEMICAL REACTIONS
As we have discussed above that there are so many types of chemical reaction which are taking place around us. Some of these reactions are very fast while others are slow. So we can categories the chemical reactions broadly into two types depending upon their rate of reaction
Thus we can define reaction rate as rate of change of concentration of a particular reactant or product per unit time.
Normally the concentration of reactants or products is expressed in moles per liter. The rate of reaction is always positive. We can write the formula of rate of a chemical reaction in terms of the change in concentration of a reactant or a product.
1. In terms of the change in concentration of reactants, the formula of rate of reaction is:
The sign of minus is used in the above formula because the concentration of a reactant decreases during a chemical reaction i.e. the change in concentration is negative. So we include the minus sign to ensure that the rate of reaction comes as a positive number.
2. In terms of the change in concentration of products, the formula of the rate of reaction is :
Unit of rate of reaction.
As the SI unit of concentration of substances is mol/liter and that of time taken is second, so the SI unit of rate of reaction is mol/liter/second or mol/l/s or mol l-1s-1
Example 1:- Suppose the concentration of a reactant in a reaction decreases from 0.8 moles per litre to 0.4 moles per litre in 10 seconds. Then the rate of this reaction is given by
Example 2:- In the same way suppose the concentration of a product in a reaction increases from 0.5 moles per litre to 0.7 moles per litre in 10 seconds. Then the rate of reaction is given by