Collision Theory

Q. The reaction A $\to$ C has activation for the forward and the backward reaction as 25 kJ and 32 kJ respectively. The $\Delta$ H for the reaction is

1. 57 kJ
2. -57 kJ
3. 7 kJ
4. -7 kJ

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. Chemical reactions with very high $E_a$ values are generally:

1. Very fast
2. Very slow
3. Spontaneous
4. Moderately fast

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. Match the following

$\begin{array}{cccc}a)& a& \left(i\right)& Activationenergyofforwardreaction\\ b)& b& \left(ii\right)& Changeinenthalpy\\ c)& c& \left(iii\right)& Activationenergyofbackwardreaction\\ d)& d& \left(iv\right)& PotentialEnergyofReactants\\ e)& e& \left(v\right)& PotentialenergyofProducts\end{array}$

1. a – (v) b – (iv) c – (i) d – (iii) e – (ii)
2. a – (i) b – (iv) c – (v) d – (iii) e – (ii)
3. a – (iv) b – (i) c – (v) d – (iii) e – (ii)
4. a – (iv) b – (i) c – (v) d – (ii) e – (iii)

Q. Higher order (>3) reactions are rare due to

1. low probability of simultaneous collision of all the reacting species
2. increase in entropy and activation energy as more molecules are involved
3. shifting of equilibrium towards reactants due to elastic collisions
4. loss of active species on 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.

Species that are formed in one step of reaction mechanism and used up in another step are called

1. catalysts

2. intermediates

3. inhibitors

4. activated complexes

Q. Match the following

1. a
2. b
3. c
4. d

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

1. False
2. True