Kerala Syllabus SAMAGRA SCERT SAMAGRA Question Pool for Class 12 Chemistry Chemical Kinetics
Rate law for the reaction A + 2B ⎯→ C is found to be Rate = k [A][B] Concentration of reactant ‘B’ is doubled, keeping the concentration of ‘A’ constant, the value of rate constant will be______.
(i) the same (ii) doubled (iii) quadrupled (iv) halved
Which of the following statements is not correct about order of a reaction.
(i) The order of a reaction can be a fractional number.
(ii) Order of a reaction is experimentally determined quantity.
(iii) The order of a reaction is always equal to the sum of the stoichiometric coefficients of reactants in the balanced chemical equation for a reaction.
(iv) The order of a reaction is the sum of the powers of molar concentration of the reactants in the rate law expression
(iii) The order of a reaction is always equal to the sum of the stoichiometric coefficients of reactants in the balanced chemical equation for a
The role of a catalyst is to change ______________.
(i) gibbs energy of reaction. (ii) enthalpy of reaction. (iii) activation energy of reaction. (iv) equilibrium constant
(iii) activation energy of reaction.
The unit of rate constant of a first order reaction is........
second-1 or s-1
Write two examples of zero order reactions?
decomposition of ammonia from the surface of gold
photochemical combination of hydrogen and
All collisions between reactant species do not lead to th formation of products.why
Those collisions in which the reactant species possess sufficent energy and proper orientation alone lead to the formation of
How did you determine the order of a complex reaction ?
it is same as the molecularity of the slowest
The equation which gives relation between temperature and rateconstant is ...........
1) Find out the order of the reaction from the following rate equation ,R=K [A][B]2
2) What is the unit of rate constant
Distinguish between order and molecularity?
Molecularity is theoritical but order is experimental
Molecularity is integral order
Molecularity greater than three is very rare why?
Beacuse the simultaneous collision of more than three molecules is very
What is a zero order reaction ? Give an example?
Rate does not depend on the concentration of the reactants
Eg: Decomposition of ammonia on Pt surface at high
The rate determining step of a complex reaction is ...........................
The rate constant of a reaction is doubled when the temperature is increased from 270C to 370C.Calculate its activation energy?
logK2/K1= Ea/2.303R [T2-T1]/T2T1
log2= Ea/2.303X 8.314 [ 310-300] / 310X 300
Half life of a firstorder reaction is 10s. Calculate its rate constant?
What is half life period? Show that half life of a first order reaction does not depends on the initial concentration?
it is the time required to reduce the half of the initial concentration of the reactant.
give the derivation t1/2 =
A first order reaction is 90% completed in 20minutes .calculate the rate constant of the reaction?
K= 2.203/t log[R0]/[R]
In a reaction A+B-----> C, the rate is doubled when the concentration of A is doubled and the rate is increased to four times when the concentration of B is doubled.Find the rate law and also the order of the reaction?
A certain reaction is second order withrepect to the reactant A and first order with respect to B.
1) write the rate equation?
2) what is the overall order?
3) what happens to rate if concentration of both A and B are doubled?
1) Rate=K [A]2[B]
3 ) Rate1= K [2A]2[2B= 8x
If units of rate and rateconstants are same, then order of the reaction is ...............
How does the catalyst increase the rate of a chemical reaction?
Catalyst decrease the activation energy of the reaction and provide an alternate path
Ester hyrolysis in acid medium is a pseudofirst order reaction .Justify?
Eventhough it is a bimolecular reaction, involving ester and water in the presence of acid, water is in large excess and its concentration does not change appreciably
Order of radioactive disintegration is
(a) Zero (b) First (c) Second (d) Third
( Half life period of radioactive substance is a constant )
A catalyst increases the rate of a chemical reaction by
(a) increasing the activation energy (b) decreasing the activation energy
(c) reacting with reactants (d) reacting with products
(b) decreasing the activation
Unit of rate constant for zero order reaction is
(a) mole L – 1 s – 1 (b) mole L – 1 s (c) mole 2 L – 2 s – 1 (d) s – 1
(a) mole L – 1 s – 1
( For zero order reaction, r = k
The substance with initial concentration of ‘a’ mole L – 1 proceeds according to zero order kinetics.
The time it takes for the completion of the reaction is ( k = rate constant).
(a) k / a (b) a / k (c) k / 2a (d) a / 2k
For the reaction 2 A + B → 3 C + D, which of the following does not express the reaction rate?
(a) d[D] / dt (b) – d[A] / 2dt (c) – d[C] / 3dt (d) – d[B] / dt
(c) – d[C] /