Chemical Kinetics · Question 17

The half life of a first order reaction is 2000 years. If the concentration after 8000 years is 0.02 M, then the initial concentration was :

1. 0.04 M
2. 0.16 M
3. 0.32 M
4. 0.08 M

For a chemical reaction 4A + 3B 6C + 9D Rate of formation of C is 6 10-2 mol L-1 s-1 and rate of disappearance of A is 4 10-2 mol L-1 s-1. The rate of reaction and amount of B consumed in interval of 10 seconds, respectively will be :

1. 10 10-2 mol L-1 s-1 and 30 10-2 mol L-1
2. 1 10-2 mol L-1 s-1 and 30 10-2 mol L-1
3. 10 10-2 mol L-1 s-1 and 10 10-2 mol L-1
4. 1 10-2 mol L-1 s-1 and 10 10-2 mol L-1

For a reaction, A B, enthalpy of reaction is -4.2 kJ mol-1 and enthalpy of activation is 9.6 kJ mol-1. The correct potential energy profile for the reaction is shown in option.

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

The slope of Arrhenius plot ( ln k v/s 1T ) of first order reaction is -5 103 K. The value of Ea of the reaction is. Choose the correct option for your answer. [Given R = 8.314 J K-1 mol-1]

1. -83 kJ mol-1
2. 41.5 kJ mol-1
3. 83.0 kJ mol-1
4. 166 kJ mol-1

An increase in the concentration of the reactants of a reaction leads to change in :

1. heat of reaction
2. threshold energy
3. collision frequency
4. activation energy

The rate constant for a first order reaction is 4.606 10-3 s-1. The time required to reduce 2.0 g of the reactant to 0.2 g is :

1. 200 s
2. 500 s
3. 1000 s
4. 100 s

If the rate constant for a first order reaction is k, the time (t) required for the completion of 99 % of the reaction is given by :

1. t = 4.606k
2. t = 2.303k
3. t = 0.693k
4. t = 6.909k

For the chemical reaction N2(g) + 3H2(g) 2NH3(g) the correct option is :

1. - d[N2]dt = 2 d[NH3]dt
2. - d[N2]dt = 12 d[NH3]dt
3. 3 d[H2]dt = 2 d[NH3]dt
4. - 13 d[H2]dt = - 12 d[NH3]dt

The correct difference between first and second order reactions is that

1. the rate of a first-order reaction does not depend on reactant concentrations; the rate of a second-order reaction does depend on reactant concentrations
2. the half-life of a first-order reaction does not depend on [A]0; the half-life of a second order reaction does depend on [A]0
3. a first-order reaction can be catalysed; a second-order reaction cannot be catalysed
4. the rate of a first-order reaction does depend on reactant concentrations; the rate of a second-order reaction does not depend on reactant concentrations

When initial concentration of the reactant is doubled, the half-life period of a zero order reaction

1. is halved
2. is doubled
3. is tripled
4. remains unchanged.