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प्रश्न
Mention the factors that affect the rate of a chemical reaction.
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उत्तर
(i) Nature of the reactant: The rate of reaction depends on the nature of the reactant. For example, ionic molecules react more quickly than covalent ones.
(ii) State of reactants: Solid reactions are slower, liquid reactions are faster, and gas reactions are very quick.
(iii) Temperature: The rate of reaction is mainly affected by temperature. Every 10°C rise in temperature increases the reaction rate by 2-3 times.
`(r_(t + 10))/r_t` = 2 − 3
This ratio is called the temperature coefficient.
There are two reasons why the reaction rate increases with temperature.
- Increasing temperature raises the average kinetic energy of reactant molecules, increasing the rate of collisions.
- As the temperature rises, the number of molecules with threshold energy increases, resulting in more active molecules. As a result, the number of effective collisions grows. As a result, the reaction rate increases.
(iv) Concentration: The rate of reaction depends on the concentration of reactants.
Rate = k × Cn
Where,
n = order of reaction
C = concentration of reactant
(v) Catalyst: The presence of a catalyst changes the rate of the reaction. It lowers the activation energy by producing a chemical intermediate, lowering the potential energy barrier. Thus, the reaction rate increases.
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|
The rate of reaction is concerned with decrease in the concentration of reactants or increase in the concentration of products per unit of time. It can be expressed as instantaneous rate at a particular instant of time and average rate over a large interval of time. A number of factors such as temperature, concentration of reactants, catalyst affect the rate of reaction. Mathematical representation of rate of a reaction is given by rate law: Rate = k[A]x [B]y x and y indicate how sensitive the rate is to change in concentration of A and B. Sum of x + y gives the overall order of a reaction. |
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