Collision Theory

Q.

What is collision frequency?

Q. An exothermic reaction $X\to Y$ has an activation energy $30kJ/mol$. If energy change $\Delta E$ during the reaction is $-20kJ/mol,$ the activation energy for the reverse reaction in $kJ/mol$ is ______.

Q. A body of mass (4m) is lying in x-y plane at rest. It suddenly explodes into three pieces. Two pieces each of mass (m) move perpendicular to each other with equal speeds (v). The total kinetic energy generated due to explosion is

Q. Reaction A + B $\to$ C + D + 38 kcal, has activation energy 20 kcal, Activation energy for reaction C + D $\to$ A + B is

1. -20 kcal
2. 58 kcal
3. 18 kcal
4. 20 kcal

Q. What are the factors that determine an effective collision?

1. Translational collision and energy of activation
2. Threshold energy and proper orientation
3. Proper orientation and steric bulk of the molecule
4. Collision frequency, threshold energy and proper orientation

Q.

Assertion (A) Rate constant determined from Arrhenius equation are fairly accurate for simple as well as complex molecules.

Reason (R) Reactant molecules undergo chemical change irrespective of their orientation during collision.

(a) Both assertion and reason are correct and the reason is correct explanation of assertion
(b) Both assertion and reason are correct, but reason does not explain assertion.
(c) Assertion is correct, but reason is incorrect
(d) Both assertion and reason are incorrect
(e) Assertion is incorrect but reason is correct.

Q. An exothermic reaction A $\to$ B has an activation energy of 17 kJ per mole of A. The heat of reaction is 40 KJ. The activation energy for the reverse reaction B $\to$ A is

1. 57 kJ
2. 17 kJ
3. 23 kJ
4. 97 kJ

Q.

In the equation $\mathrm{k}={\mathrm{PZ}}_{\mathrm{AB}}{\mathrm{e}}^{\frac{-\mathrm{Ea}}{\mathrm{RT}}}$ what is the term used for describing P?

Q.

What is the probability of reaction with molecularity higher than three very rare?

Q.

Which of the following statements is incorrect about the collision theory of chemical reaction?

(a) It considers reacting molecules or atoms to be hard spheres and ignores their structural features
(b) Number of effective collisions determines the rate of reaction
(c) Collision of atoms or molecules possessing sufficient threshold energy results into the product formation
(d) Molecules should collide with sufficient threshold energy and proper orientation for the collision to be effective

Q. The potential energy of the products is lesser than that of the reactants in an endothermic reaction.

1. False
2. True

Q.

Assertion (A) All collision of reactant molecules lead to product formation.

Reason (R) Only those collisions in which molecules have correct orientation and sufficient kinetic energy lead to compound formation.

(a) Both assertion and reason are correct and the reason is correct explanation of assertion
(b) Both assertion and reason are correct, but reason does not explain assertion.
(c) Assertion is correct, but reason is incorrect
(d) Both assertion and reason are incorrect
(e) Assertion is incorrect but reason is correct.

Q.

What is collision theory of chemical reaction ?

Q. Choose the incorrect statement regarding collision theory:

1. The minimum amount of energy the colliding molecules must possess to participate in a chemical reaction is the threshold energy.
2. For a collision to be effective, orientation of the molecules does not matter.
3. For a collision to be effective, kinetic energy of molecules does matter.
4. Kinetic energy and orientation factor both play an important role for an effective collision to take place

Q.

What happens to the total energy after an elastic collision?

Q.

In most cases, for a rise of 10K temperature, the rate constant is doubled or tripled. This is due to the reason that ?

1. None of these

2. Collision frequency increases by a factor 2 to 3

3. Fraction of molecules possessing threshold energy increases by a factor of 2 to 3

4. Activation energy is lowered by a factor of 2 to 3

Q. 19.The rate constant varies as logk=10-9.6×10 2/T then the activation energy of the reaction

Q. If for a reaction, $A\to B$, $\Delta H=-10{\text{kJ mol}}^{-1}$ and $E_a=50{\text{kJ mol}}^{-1}$, the energy of activation for the reaction, $B\to A$ will be:

1. $40{\text{kJ mol}}^{-1}$
2. $50{\text{kJ mol}}^{-1}$
3. $-50{\text{kJ mol}}^{-1}$
4. $60{\text{kJ mol}}^{-1}$

Q. Considering density, frequency and velocity as fundamental quantities find the dimensions of 1) Angular momentum 2) universal gas constant ?

Q. 13. If activation energy of a backward reaction is -20 kJ/mol and that of forward reaction is 40kJ/mol, then enthalpy change for the reaction is 1. 20kJ/mol 2. 60kJ/mol 3. -20kJ/mol 4. -60kJ/mol Kindly explain with graph

Q.

All energetically effective collisions do not result in a chemical change. Explain with the help of an example.

Q. For the equilibrium, A(g) gives B(g), delta is -40kJ/mol. If the ratio of the activation energies of the forward (Ef) and reverse (Eb) rxn is 2/3 then :(in kj/mol)

Q. Addition of catalyst at 300K increases the rate by a factor of 36.By how many kJ activation energy of catalysed pathway is less than the activation energy of original pathway?(\log6=0.78 R=8.3) 1.6kJ 2.9kJ 3.10kJ 4.12kJ

Q.

For a certain reaction large fraction of molecules has energy more than the threshold energy, yet the rate of reaction is very slow. Why?

Q. Define collision frequency. Give an example for Pseudo-first order reaction.

Q. What are effective collisions?

1. Collisions leading to the transformation of reactants to products
2. formation of activated complex
3. collison between two reactant to decrease the activation energy
4. collison between two reactant to overcome activation energy barrier

Q. Helium atom is two times heavier than a hydrogen molecule $\left(H_2\right)$. At $298\text{K}$, the average kinetic energy of helium atom is

1. Two times that of a hydrogen molecule
2. Half that of a hydrogen molecule
3. Four times that of a hydrogen molecule
4. Same as that of a hydrogen molecule

Q. An exothermic reaction $X\to Y$ has an activation energy $30kJ/mol$. If energy change $\Delta E$ during the reaction is $-20kJ/mol,$ the activation energy for the reverse reaction in $kJ/mol$ is ______.

Q. A chemical reaction in which energy is liberated is called :

1. exothermic reaction
2. endothermic reaction
3. physical change
4. photochemical reaction

Q. What happens when the energy of a reaction if more than threshold energy? Is such a situation possible?