Find the molecularity and order of the following reaction : CH 3 COOCH 3 + H 2 O → CH 3 COOH + CH 3 OH

The order is defined as the power to which the concentration term of a substance is raised in the rate equation. The sum of the powers of the concentrations of various substances in the rate equation is equal to overall order of a reaction. CH 3 COOCH 3 ( aq ) + H 2 O → CH 3 COOH ( aq ) + CH 3 OH ( aq ) Since H 2 O is taken in excess in the given equation, its concentration does not affect the rate and hence, the given reaction is a first order reaction. However, the molecularity of this reaction is 2 as 2 molecules of the reactants react to form product.

Prove that half life period of a first order reaction is independent of the initial concentration of the reactants.

From the integrated rate equation for a first order reaction, k = 2 . 303 t log A ∘ A At t 1 2 , A = A ∘ 2 . Substituting in the above equation, k = 2 . 303 t 1 2 log A ∘ A ∘ 2 k = 2 . 303 t 1 2 log 2 t 1 2 = 2 . 303 k × 0 . 301 t 1 2 = 0 . 693 k This proves that the half life period of a first order reaction doesn't depend upon the initial concentration of the reactants.

What is zero order reaction? Write formula also.

Reaction in which concentration of the reactants do not change with time and the concentration rates remain constant throughout are called zero order reactions. The rate of these reactions is always equal to the rate constant of specific reactions because the rate of these reactions is equal to the zeroth power of concentrations. The formula of half life period for a zero order reaction is: t 1 2 = R 0 2 k

Explain the dependence of rate of reaction on temperature.

The progress of a reaction depends on the temperature of the reacting substances. The increase of temperature increases the rate of reaction while decrease of temperature lowers the rate of reaction. The rate of the reaction increases with increase of temperature due to the increase in the number of collisions and due to increase in the fraction of molecules having energy equal to and greater than the threshold value. For most of the chemical reactions, there is a two-fold increase in the rate for each 10 ℃ rise in temperature. Arrhenius gave an empirical equation for the variation of the rate of reaction with temperature. The variation of rate constant with temperature is given by Arrhenius as : k = A exp ( - E a RT ) Where, A =frequency factor E a = activation energy R = gas constant T = temperature

Determine the expression of half life period for first order reaction.

Half life period is the time in which concentration of reactant is reduced to one half of the initial concentration. It is denoted by t 1 2 . We know that f or first order reaction K = 2 . 303 t log a - x a t = 2 . 303 K log a - x a If t = t 1 2 and x = a 2 , then t 1 2 = 2 . 303 K log a a - a 2 t 1 2 = 2 . 303 K log 2 t 1 2 = 2 . 303 K × 0 . 3010 ∵ log 2 = 0 . 3010 t 1 2 = 0 . 693 K

What is threshold energy?

The minimum kinetic energy that all colliding molecules must have in order to make the effective collisions between two reactant molecules, is called threshold energy.

Determine the expression of rate constant for zero order reaction.

The rate of a zero order reaction does not change with the concentration of the reactant. For a zero order reaction like R → P , rate can be written as, Rate = - d R dt = k R 0 Any quantity raised to power zero equals unity, so Rate = - d R dt = k × 1 d R = - k dt On integrating both the sides, R = - kt + I - 1 where I is the constant of integration. Now, at t = 0 , the concentration of the reactant R = R ∘ , where R ∘ is the initial concentration of the reactant. Substituting this in equation 1 - R ∘ = k × 0 + I R ∘ = I Substituting this value in equation 1 - R = - kt + R ∘ k = R ∘ - R t

Derive an expression of rate constant for zero order reaction.

The rate of a zero order reaction does not change with the concentration of the reactant. For a zero order reaction like R → P , rate can be written as, Rate = - d R dt = k R 0 Any quantity raised to power zero equals unity, so Rate = - d R dt = k × 1 d R = - k dt On integrating both the sides, R = - kt + I - 1 where I is the constant of integration. Now, at t = 0 , the concentration of the reactant R = R ∘ , where R ∘ is the initial concentration of the reactant. Substituting this in equation 1 - R ∘ = k × 0 + I R ∘ = I Substituting this value in equation 1 - R = - kt + R ∘ k = R ∘ - R t

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EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR CHEMISTRY>Chapter -1 - Chemical Kinetics>Chattisgarh Board-2019>Q 9

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What is temperature coefficient? Write formula.

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