Chemical Kinetics

The ratio of 14C12C in a piece of wood is 18 part that of atmosphere. If half life of 14C is 5730 years, the age of wood sample is years.

The following data were obtained during the first order thermal decomposition of a gas A at constant volume : A(g) 2B(g) + C(g) [figure] The rate constant of the reaction is 10-2 s-1 (nearest integer)

Integrated rate law equation for a first order gas phase reaction is given by (where Pi is initial pressure and Pt is total pressure at time t)

1. k = 2.303t Pi(2Pi - Pt)
2. k = 2.303t (2Pi - Pt)Pi
3. k = 2.303t Pi(2Pi - Pt)
4. k = 2.303t 2Pi(2Pi - Pt)

r = k[A] for a reaction, 50% of A is decomposed in 120 minutes. The time taken for 90% decomposition of A is minutes.

The rate of a first order reaction is 0.04 mol L-1 s-1 at 10 minutes and 0.03 mol L-1 s-1 at 20 minutes after initiation. Half life of the reaction is minutes. (Given 2 = 0.3010, 3 = 0.4771)

NO2 required for a reaction is produced by decomposition of N2O5 in CCl4 as by equation 2N2O5(g) 4NO2(g) + O2(g) The initial concentration of N2O5 is 3 mol L-1 and it is 2.75 mol L-1 after 30 minutes. The rate of formation of NO2 is x 10-3 mol L-1 min-1, value of x is . (nearest integer)

For a reaction taking place in three steps at same temperature, overall rate constant K = K1 K2K3. If Ea1, Ea2 and Ea3 are 40, 50 and 60 kJ/mol respectively, the overall Ea is kJ/mol.

The half-life of radioisotope bromine - 82 is 36 hours. The fraction which remains after one day is 10-2. (Given antilog 0.2006 = 1.587)

Consider the following data for the given reaction 2HI(g) H2(g) + I2(g) [figure] The order of the reaction is .

Time required for completion of 99.9% of a First order reaction is times of half life (t1/2) of the reaction.