Effect of Catalyst

Q.

How to remember all organic chemistry reactions?

Q.

What is Biocatalyst give example?

Q.

For the system 3A + 2B $\rightleftharpoons$ C, the expression for equilibrium constant is

1. ([3A][2B])/[C]

2. [C]/([3A][2B])

3. ([A]³[B]²)/[C]

4. [C]/([A]³[B]²)

Q.

Is water boiling exothermic or endothermic?

Q.

Why does the slowest step considered a rate determining step of the reaction?

Q.

What does a negative activation energy mean?

Q. For the homogeneous elementary reaction, ABC, the unit of rate constant is(2) s-1 mol L-1-1ST(3) s1 mo-1 L

Q.

Which of the following statement is not correct for the catalyst?
(a) It catalysts the forward and backward reactions to the same extent
(b) It alters$\Delta G$ of the reaction
(c) It is a substance that does not change the equilibrium constant of the reaction
(d) It provides an alternate mechanism by reducing activation energy between reactants and products

Q.

The role of a catalyst is to change ...... .
(a) Gibbs energy of reaction
(b) enthalpy of reaction
(c) activation energy of reaction
(d) equilibrium constant

Q.

Heat is evolved during

1. Endothermic reaction

2. Displacement reaction

3. Combination reaction

4. Exothermic reaction

Q. A catalyst:
(i) increases the average kinetic energy of reacting molecules
(ii) decrease the activation energy
(iii) alters the reaction mechanism
(iv) increases the frequency of collisions of reacting species.
The true statements are:

1. $i,ii,iii$
2. $i,iii$
3. $ii,iv$
4. $ii,iii$

Q.

Assertion (A) The enthalpy of reaction remains constant in the presence of a catalyst.

Reason (R) A catalyst participating in the reaction forms different activated complex and lowers down the activation energy but the difference in enrgy of reactant and product remains the same.

(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.

Platinised asbestos is used as a catalyst in the manufacture of:

1. $\mathrm{HCl}$

2. ${\mathrm{H}}_2{\mathrm{SO}}_4$

3. ${\mathrm{HNO}}_3$

4. None of the above

Q.

Give two tests for identification of water vapour.

Q.

Mark the incorrect statements.
(a)Catalyst provides an alternative pathway to reaction mechanism
(b)Catalyst raises the activation energy
(c)Catalyst lowers the activation energy
(d)Catalyst alters enthalpy change of the reaction

Q. A catalyst

1. Can either increase or decrease the free energy change depending on what catalyst we use
2. Increases the free energy change in the reaction
3. Decreases the free energy change in the reaction
4. Does not increase or decrease the free energy change in the reaction

Q.

The energy of activation for a reaction at $300K$ is $100kJmo{l}^{-1}$. For same concentration, presence of a catalyst lowers the energy of activation by $75\%$. Calculate the value of
${\log }_{10}\left(\frac{r_2}{r_1}\right)$
$r_2=\text{rate in presence of catalyst}$
$r_1=\text{rate in absence of catalyst}$

1. 13.06
2. 7.94
3. 10.02
4. 3.21

Q. What is meant by reaction co-ordinate in the statement:
"The energy required to form this intermediate, called the activated complex is known as activation energy. Figure 4.7 is obtained by plotting potential energy versus reaction co-ordinate. Reaction co-ordinate represents the profile of energy change when reactants change into products"
Please explain the meaning of the sentence and the term reaction coordinate in an easy way.
(Chemistry part 1, Class 12, NCERT, Chapter: Chemical Kinetics Page: 112)

Q.

Describe how does the enthalpy of reaction remain unchanged when a catalyst is used in the reaction?

Q. What are the effects of catalyst on rate of chemical reaction?

Q.

The energy of activation for a reaction at $300K$ is $100kJmo{l}^{-1}$. For same concentration, presence of a catalyst lowers the energy of activation by $75\%$. Calculate the value of
${\log }_{10}\left(\frac{r_2}{r_1}\right)$
$r_2=\text{rate in presence of catalyst}$
$r_1=\text{rate in absence of catalyst}$

1. 13.06
2. 10.02
3. 7.94
4. 3.21

Q.

Slowest step of the multistep reaction is known as _________

Q.

Which is a characteristic of a catalyst?

1. It Initiates the reaction.

2. It alters the rate of reaction.

3. It Increases the average kinetic energy of the molecule

4. Both B and C.

Q.

Select the correct statement from the following

1. Catalyst are active only in solution

2. The ratio of mixture at equilibrium is not changed by catalyst

3. Equilibrium constant changes with addition of catalyst

4. Catalyst increases the rate of forward reaction

Q. Assertion :A catalyst does not alter the equilibrium constant of a reaction. Reason: The catalyst forms a complex with the reactants and provides an alternate path with lower energy of activation for the reaction; the forward and back ward reactions are affected to the same extent.

1. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
2. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
3. Assertion is correct but Reason is incorrect
4. Both Assertion and Reason are incorrect

Q. A catalyst increases the rate of reaction because it:

1. increases the activation energy
2. decreases the activation energy
3. decreases collision diameter
4. increases the temperature coefficient

Q.

What is the statement of rate law?

Q.

The activation energy of the reaction:
$A+B\to$ Products is 105.73 KJ/mol. At ${40}^{\circ }C$ , the products are formed at the rate of 0.133 mol $L^{-1}mi{n}^{-1}$ the rate of formation of products at ${80}^{\circ }C$ will be

1. $13.3mol{L}^{-1}mi{n}^{-1}$
2. $17.8mol{L}^{-1}mi{n}^{-1}$
3. $Noneoftheabove$
4. $5.6mol{L}^{-1}mi{n}^{-1}$

Q.

Describe your observations when potassium nitrate crystals are heated strongly in a test tube and a glowing splint is healed near the mouth of the test tube. Write a fully balanced chemical equation for the decomposition of potassium nitrate crystals.

Q.

State the property of sulphur dioxide which causes potassium permanganate to change its colour from purple to colourless?