(a) Define the following:
(i) Order of a reaction
(ii) Elementary step in a reaction
(b) A first order reaction has a rate constant value of 0.00510 min^-1.  If we begin with 0.10 M concentration of the reactant, how much of the reactant will remain after 3.0 hours?

(a) Explain the following terms:
(i) Rate of a reaction
(ii) Activation energy of a reaction
(b) The decomposition of phosphine (PH₃) proceeds according to the following equation:
4PH₃(g) \(\to\)P₄ (g) + 6H₂ (g)
It is found that the reaction follows the following rate equation:
Rate = k [PH₃]
The half-life of PH₃ is 37.9 s at 120 ^oC.
(i) How much time is required for 3/4^th of PH₃ to decompose?
(ii) What fraction of the original sample of PH₃ remains behind after 1 minutes?

(a) Explain the following terms:
(i) Order of a reaction
(ii) Molecularity of a reaction
(b) The rate of a reaction increases four times when the temperature changes from 300 k to  320 K.  Calculate the energy of activation of the reaction, assuming that it does not change with temperature.
(R = 8.314 J K^-1 mol^-1)

What is Arrhenius equation to describe the effect of temperature on rate of a reaction? How can it be used to calculate the activation energy of a reaction?

Describe briefly the dependence of reaction rate of a chemical reaction on temperature. Explain the effect of temperature on the rate constant of a reaction.

For the hydrolysis of methyl acetate in aqueous solution, the following results were obtained:

(i) Show that It follows pseudo first order reaction, as the concentration of water remains constant.
(ii) Calculate the average rate of reaction between the time interval 30 to 60 seconds. [Given log 2 = 0.3010, log 4 = 0.6021]

(a) For a reaction A + B⟶P, the rate is given by Rate = k[A] [B]²
(i) How is the rate of reaction affected if the concentration of B is doubled?
(ii) What is the overall order of reaction if A is present in large excess?
(b) A first order reaction takes 30 minutes for 50% completion. Calculate the time required for 90%  completion of this reactions. (log 2 = 0.3010)

Following is a graph between reaction co-ordinate and potential energy. Explain how a catalyst influence the reaction.

In a given graph, if ‘E’ is the activation energy for a given reaction, explain how temperature influences the rate of reaction.

In the following figure, orientations of reaction molecules are shown. Explain the influence of orientation of molecules in a chemical reaction?

The time required for 10% completion of a first order reaction at 298 K is equal to that required for its 25% completion at 318 K. If the pre-exponential factor for the reaction is 3.56 \(\times 10 ^{9} s^{-1}\), calculate its rate constant at 318 K and also the energy of activation.

For the reaction, N₂O₅(g) = 2 NO₂(g) + 0.5 O₂ (g), calculate the mole fraction of N₂O₅ (g) decomposed at a constant volume and temperature, if the initial presure is 600 mm Hg and the pressure at any time is 960 mm Hg. Assume ideal gas behaviour.

The energy change accompanying the equilibrium reaction A \(\rightleftharpoons \) B is -33.0 kJ mol-1. Calculate
(i) Equilibrium constant K_c for the reaction at 300 K
(ii) Energy of activation forward and backward reaction (E_f and E_b) at 300 K. Given that Ef and Assume that pre-exponential factor is same for forward and backward reaction.

Two first reactions proceed at the same rate at 15^oC when started with same initial concentration. The temperature coefficient of the first reaction is 2 while that of the second reaction is 3. What will be the ratio of the rates of these reactions at 55^oC ?

When inversion of surcose is studied at pH = 5, the half-life period is always found to be 500 minutes irrespective of any initial concentration but when it is studied at pH = 6, the half-life period is found to be 50 minutes. Derive the rate law expression for the inversion of surcose.