Chemical Kinetics Test

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Chemical Kinetics Test - 30

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Question 1
1 / -0

Which statements describe the condition(s) required for a successful formation of a product in a reaction ?

A
The collision must involve a sufficient amount of energy, provided from the motion of the particles, to overcome the activation energy

B
The relative orientation of the particles has little or no effect on the formation of the product

C
The relative orientation of the particles has an effect only if the kinetic energy of the particles is below some minimum value

D
The relative orientation of the particles must allow for formation of the new bonds in the product

E
The energy of the incoming particles must be above a certain minimum value and the relative orientation of the particles must allow for formation of new bonds in the product

Solution

The statement (E) describe the conditions required for a successful formation of a product in a reaction.
The energy of the incoming particles must be above a certain minimum value (called activation energy) and the relative orientation of the particles must allow for formation of new bonds in the product.
Question 2
1 / -0

Based on the following reaction and rate data:
$$\displaystyle A\left( g \right) +B\left( g \right) \rightarrow products$$

Experiment $$[A]$$ mol/L $$[B]$$ mol/L Initial Rate (M/s)
1 0.060 0.010 0.040
2 0.030 0.010 0.040
3 0.030 0.020 0.080
What is the order of the reaction with respect to $$A$$?

A
0

B
1

C
2

D
3

E
4

Solution

Analyzing from row $$1$$ and $$2$$ ,change in concentration of $$A$$ is not affecting initial rate of reaction so reaction is zero order with respect to $$A$$.
Question 3
1 / -0

Assertion: Increasing the concentration of reactants will cause a reaction to proceed faster.
Reason: More reactants lowers the activation energy of a reaction.

A
Both Assertion and Reason are true and Reason is the correct explanation of Assertion

B
Both Assertion and Reason are true but Reason is not the correct explanation of Assertion

C
Assertion is true but Reason is false

D
Assertion is false but Reason is true

E
Both Assertion and Reason are false

Solution

Assertion: Increasing the concentration of reactants will cause a reaction to proceed faster. The rate of the reaction is proportional to the reactant concentration.
Reason: More reactants do not lower the activation energy of a reaction.
At a given temperature, the activation energy is constant.
Assertion is true but Reason is false.
Question 4
1 / -0

What does the exponential factor represent?

A
The total number of reactants in a reaction.

B
The amount of energy needed to start a chemical reaction.

C
The fraction of reactants that have approached the activation energy hill and made it over per number of attempts.

D
The fraction of reaction energy given off per unit of time.

E
The fraction of products that have approached the activation energy hill and made it over per number of attempts.

Solution

The exponential factor represents the fraction of "reactants" that have approached the activation energy hill and made it over per number of attempts.
Question 5
1 / -0

In a multistep chemical process, the rate-limiting step is the step in the reaction with the :

A
Highest activation energy & fastest reaction rate

B
Highest activation energy & slowest reaction rate

C
Lowest activation energy & fastest reaction rate

D
Lowest activation energy & slowest reaction rate

E
Greatest concentration of the reactants and products

Solution

The rate determining step is the slowest step of a chemical reaction that determines the speed (rate) at which the overall reaction proceeds. The rate determining step can be compared to the neck of a funnel. In above above plot step $$A$$ is rate determining step.
Question 6
1 / -0

Refer to the heating curve for $$H_{2}O$$ above.
Where is the temperature of $$H_{2}O$$ changing at $$\dfrac {1^{\circ}C}{g.cal}$$?

A
A

B
B

C
C

D
D

E
E

Solution

$$1^oC$$/g.cal is specific heat for liquid water so $$C$$ region represents this.
Question 7
1 / -0

Which letter shows the potential energy of the products?

A
A

B
B

C
C

D
D

E
E

Solution

The letter $$D$$ shows the potential energy of the products.
The letter $$A$$ shows the potential energy of the transition state.
The letter $$B$$ shows the energy of activation.
The letter $$C$$ shows the enthalpy change for the reaction.
The letter$$ E$$ shows the activation energy of the backward reaction.
Question 8
1 / -0

Based on the following reaction and rate data:
$$\displaystyle A\left( g \right) +B\left( g \right) \rightarrow products$$

Experiment $$[A]$$ mol/L $$[B]$$ mol/L Initial Rate (M/s)
1 0.060 0.010 0.040
2 0.030 0.010 0.040
3 0.030 0.020 0.080
What is the order of the reaction with respect to $$B$$?

A
0

B
1

C
2

D
3

E
4

Solution

Analyzing from row $$2$$ and $$3$$ ,when change in concentration of $$B$$ is doubled then initial rate of reaction also doubles so rate of reaction is varying in same order as concentration of B. Hence reaction is first order with respect to $$B$$.
Question 9
1 / -0

Refer to the heating curve for $$H_{2}O$$ above.
Which region indicates a solid?

A
A

B
B

C
C

D
D

E
E

Solution
Question 10
1 / -0

Statement I : Catalysts decrease the rate of a chemical reaction
Because
Statement II : Catalysts decrease activation energy

A
Statement 1 and Statement 2 are correct and Statement 2 is the correct explanation of Statement 1 .

B
Both the Statement 1 and Statement 2 are correct and Statement 2 is not the correct explanation of Statement 1.

C
Statement 1 is correct but Statement 2 is not correct.

D
Statement 1 is not correct but Statement 2 is correct.

E
Both the Statement 1 and Statement 2 are not correct.

Solution

Answer (D)

To increase the rate of a reaction you need to increase the number of successful collisions. One possible way of doing this is to provide an alternative way for the reaction to happen which has a lower activation energy.so catalysts are added to reaction mixture.