A first order reaction is found to have a rate constant, k = 5 . 5 × 10 - 14 s - 1 . Find the half life of the reaction.

Given : k = 5 . 5 × 10 - 14 s - 1 Solution : Half life period is the time in which the molar concentration of reactants is reduced to half. Half life period of first order reactions : t 1 2 = 0 . 693 k So, t 1 2 = 0 . 693 5 . 5 × 10 - 14 = 1 . 26 × 10 13 s Hence, the value of half life of the reaction comes out to be 1 . 26 × 10 13 s .

The decomposition of ammonia on a platinum surface is a zero-order reaction. If the rate constant is 4 × 10 - 3 Mol . L - 1 . s - 1 , how long will it take to reduce the initial concentration of ammonia from 0 . 1 M to 0 . 064 M .

We have given, Decomposition of ammonia is a zero-order reaction. Initial concentration, R 0 = 0 . 1 M Final concentration, R t = 0 . 064 M Then time, t = ? From the expression for a zero-order rate constant, required time t = [ R ] ∘ − [ R ] t k Substituting the given values, t = [ 0 . 1 − 0 . 064 ] 4 × 10 - 3 = 0 . 936 4 × 10 - 3 t = 234 secs So, the time taken to reduce the initial concentration of ammonia from 0 . 1 M to 0 . 064 M = 234 sec

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Important Questions on Chemical Kinetics

EASY

Chemistry>Physical Chemistry>Chemical Kinetics>Integrated Rate Law for Zero and First Order Reactions

Derive an integrated rate equation for a first order reaction.

MEDIUM

Chemistry>Physical Chemistry>Chemical Kinetics>Integrated Rate Law for Zero and First Order Reactions

The given plots represent the variation of the concentration of a reactant $R$ with time for two different reactions $(i) and (ii)$ . The respective orders of the reaction are
(i) Question Image

(ii) Question Image

MEDIUM

Chemistry>Physical Chemistry>Chemical Kinetics>Integrated Rate Law for Zero and First Order Reactions

A first order reaction is found to have a rate constant,

k = 5.5 \times 10^{- 14} s^{- 1}

. Find the half life of the reaction.

EASY

Chemistry>Physical Chemistry>Chemical Kinetics>Integrated Rate Law for Zero and First Order Reactions

The decomposition of ammonia on a platinum surface is a zero-order reaction. If the rate constant is

4 \times 10^{- 3} Mol . L^{- 1} . s^{- 1}

, how long will it take to reduce the initial concentration of ammonia from

0.1 M to 0.064 M

EASY

Chemistry>Physical Chemistry>Chemical Kinetics>Integrated Rate Law for Zero and First Order Reactions

What is a trophic level in an ecosystem ? What is ‘standing crop’ with reference to it?

EASY

Chemistry>Physical Chemistry>Chemical Kinetics>Integrated Rate Law for Zero and First Order Reactions

The rate constant for a first order reaction is

60 s^{- 1} .

How much time will it take to reduce the initial concentration of the reactant to its

1 / 16^{th}

value?

HARD

Chemistry>Physical Chemistry>Chemical Kinetics>Integrated Rate Law for Zero and First Order Reactions

Derive an integrated rate equation for rate constant of a first order reaction.

EASY

Chemistry>Physical Chemistry>Chemical Kinetics>Integrated Rate Law for Zero and First Order Reactions

What is primary production?

MEDIUM

Chemistry>Physical Chemistry>Chemical Kinetics>Integrated Rate Law for Zero and First Order Reactions

Describe the DDT biomagnification occurring in an aquatic food chain. State the negative effects the process has on the organisms at the last trophic level of the food chain.

MEDIUM

Chemistry>Physical Chemistry>Chemical Kinetics>Integrated Rate Law for Zero and First Order Reactions

Give a diagrammatic representation of energy flow through different trophic levels.

MEDIUM

Chemistry>Physical Chemistry>Chemical Kinetics>Integrated Rate Law for Zero and First Order Reactions

A first order reaction is

50 %

completed in

40

minutes at

300 K

and in

20

minutes at

320 K

. Calculate the activation energy of the reaction. (Given :

\log 2 = 0 \cdot 3010, \log 4 = 0 \cdot 6021, R = 8 \cdot 314 {JK}^{- 1} {mol}^{- 1}

)

MEDIUM

Chemistry>Physical Chemistry>Chemical Kinetics>Integrated Rate Law for Zero and First Order Reactions

How is the detritus food chain connected with the grazing food chain in a natural ecosystem?

HARD

Chemistry>Physical Chemistry>Chemical Kinetics>Integrated Rate Law for Zero and First Order Reactions

In a reaction, the initial concentration of the reactants increases fourfold and the rate becomes eight times its initial value. The order of the reaction is -

EASY

Chemistry>Physical Chemistry>Chemical Kinetics>Integrated Rate Law for Zero and First Order Reactions

A first order reaction takes

40

minutes for

30 %

decomposition. Calculate

t_{1 / 2}

EASY

Chemistry>Physical Chemistry>Chemical Kinetics>Integrated Rate Law for Zero and First Order Reactions

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

HARD

Chemistry>Physical Chemistry>Chemical Kinetics>Integrated Rate Law for Zero and First Order Reactions

Lakshmi wants to buy few bangles and ear drops. Each bangle costs

Rs . 5

and each ear drop costs

Rs . 10 .

She should buy atleast

6

bangles and atmost

2

ear drops. If she buys

x

bangles and

y

ear drops with minimum expenditure, then the formulation for this linear programming is

EASY

Chemistry>Physical Chemistry>Chemical Kinetics>Integrated Rate Law for Zero and First Order Reactions

The objective function of LPP defined over the convex set attains its optimum value at

MEDIUM

Chemistry>Physical Chemistry>Chemical Kinetics>Integrated Rate Law for Zero and First Order Reactions

Explain energy flow in ecosystem.

EASY

Chemistry>Physical Chemistry>Chemical Kinetics>Integrated Rate Law for Zero and First Order Reactions

Explain the role of the ‘first trophic level’ in an ecosystem.

EASY

Chemistry>Physical Chemistry>Chemical Kinetics>Integrated Rate Law for Zero and First Order Reactions

If 20J of energy is trapped at producer level, then how much energy will be available to peacock as food in the following chain?
plant

\to

mice

\to

snake

\to

peacock

What are the components of aggregate demand in a two-sector economy?

Important Questions on Chemical Kinetics

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