AIPMT 2010 Physics and Chemistry Paper

Let order of reaction with respect to A is x and with respect to B is y. Thus,
rate =k[A]x[B]y
For the given cases,
(I) rate =k(0.1)x(0.1)y=6.0×10−3
(II) rate =k(0.3)x(0.2)y=7.2×10−2
(III) rate =k(0.3)x(0.40)y=2.88×10−1
(IV) rate =(0.4)x(0.1)y=2.40×10−2
On dividing Eq. (i) by (IV), we get
(‌

0.1

0.4

)x(‌

0.1

0.1

)y=‌

6.0×10−3

2.4×10−2

Or (‌

1

4

)x=(‌

1

4

)1
x=1
On dividing Eq. (II) by (III), we get
(‌

0.3

0.3

)x(‌

0.2

0.4

)y=‌

7.2×10−2

2.88×10−1

‌‌
or ‌‌(‌

1

2

)y=‌

1

4

Or (‌

1

2

)y=(‌

1

2

)2
∴‌‌y=2
Thus, rate law is,
rate =k[A]1[B]2 or =k[A][B]2