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प्रश्न
In a reaction between A and B, the initial rate of reaction (r0) was measured for different initial concentrations of A and B as given below:
| A/mol L−1 | 0.20 | 0.20 | 0.40 |
| B/mol L−1 | 0.30 | 0.10 | 0.05 |
| r0/mol L−1 s−1 | 5.07 × 10−5 | 5.07 × 10−5 | 1.43 × 10−4 |
What is the order of the reaction with respect to A and B?
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उत्तर
Suppose the order of the reaction with respect to A is m and with respect to B is n
∴ r0 = k[A]m [B]n
For the given data, we have
5.07 × 10−5 = k (0.20)m × (0.30)n ...(i)
5.07 × 10−5 = k (0.20)m × (0.10)n ...(ii)
1.43 × 10−4 = k (0.40)m × (0.05)n ...(iii)
Dividing eq. (i) by eq. (ii), we have
`(5.07 xx 10^-5)/(5.07 xx 10^-5) = (k (0.20)^m xx (0.30)^n)/(k (0.20)^m xx (0.10)^n)`
or 1 = (3)n
or n = 0
Dividing eq. (iii) by eq. (ii) and putting the value of n, we get
`(1.43 xx 10^-4)/(5.07 xx 10^-5) = (k (0.40)^m xx (0.05)^0)/(k (0.20)^m xx (0.10)^0)`
or, `(1.43 xx 10^-4)/(5.07 xx 10^-5)` = 2m
or (2)m = 2.82
or, m log10 2 = log10 2.82 = 0.45
or, m = `0.45/(log_10 2)`
= `0.45/0.3010`
= 1.49
= 1.50
Hence, order with respect to A = 1.5 and order with respect to 8 = 0.
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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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