NEET Chemistry Chemical Kinetics Questions Solved

NEET - 2012

In a reaction, A+B          Product, rate is doubled when the concentration of B is doubled, and rate increases by a factor of 8 when the concentrations of both the reactants (A and B) are doubled. Rate law for the reaction can be written as

(a) Rate = k[A][B]2

(b) Rate = k[A2][B2]

(c) Rate = k[A][B]

(d) Rate = k[A]2 [B]

(d) Let the order of reaction with respect to A and B is x and y respectively. So, the rate law can be given as         R = kAxBy           .........(i)

When the concentration of only B is doubled, the rate is doubled, so

                     R1=kAx2By = 2R   ......(ii)

If concentrations of both the reactants A and B are doubled, the rate increases by a factor of 8, so

                  R'' = k[2A]x[2B]y = 8R       .....(iii)              k2x2y[A]X[B]y = 8R               .....(iv)From Eq. (i) and (ii), we get            2RR=Ax2ByAxBy                      2=2y                 y = 1From Eq. (i) and (iv), we get          8RR= 2x2yAxByAxByor                8 = 2x2ySubstitution of the value of y gives,                    8 = 2x21                    4 = 2x                22 = 2x                x = 2

Substitution of the value of x and y in Eq. (i) gives,

R = kA2B

Difficulty Level:

  • 21%
  • 18%
  • 11%
  • 52%