Chemical Kinetics

Consider a complex reaction taking place in three steps with rate constants k1, k2 and k3 respectively. The overall rate constant k is given by the expression k= k1k3k2. If the activation energies of the three steps are 60, 30 and 10 kJ mol-1 respectively, then the overall energy of activation in kJ mol-1 is . (Nearest integer)

For the thermal decomposition of N2O5(g) at constant volume, the following table can be formed, for the reaction mentioned below. 2N2O5(g) 2N2O4(g)+O2(g) [figure] x= 10-3 atm [nearest integer] Given : Rate constant for the reaction is 4.606 10-2 s-1.

Which of the following graphs most appropriately represents a zero order reaction?

1. [figure]
2. [figure]
3. [figure]
4. [figure]

A B The molecule A changes into its isomeric form B by following a first order kinetics at a temperature of 1000 K. If the energy barrier with respect to reactant energy for such isomeric transformation is 191.48 kJ mol-1 and the frequency factor is 1020, the time required for 50\% molecules of A to become B is picoseconds (nearest integer). [R=8.314 J K-1 mol-1 ]

Which of the following statement is not true for radioactive decay?

1. Half life is 2 times of 1rate constant.
2. Decay constant increases with increase in temperature.
3. Decay constant does not depend upon temperature.
4. Amount of radioactive substance remained after three half lives is 18th of original amount.

Consider the given figure and choose the correct option : [figure]

1. Activation energy of both forward and backward reaction is E1 + E2 and reactant is more stable than product.
2. Activation energy of forward reaction is E1 + E2 and product is more stable than reactant.
3. Activation energy of backward reaction is E1 and product is more stable than reactant.
4. Activation energy of forward reaction is E1 + E2 and product is less stable than reactant.