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Chemical Kenetics

Chemical Kenetics

1- Consider the following elementary steps that make up the mechanism of a certain reaction1

1. 3A→B+C
2. B+2D→C+F

2- What is the rate law for step 1 of this reaction? Express your answer in standard MasteringChemistry notation. For example, if the rate law is k[A][C] 3 type k*[A]*[C]^3.

3- What is the rate law for step 2 of this reaction?Express your answer in standard MasteringChemistry notation. For example, if the rate law is k[A][C] 3 type k*[A]*[C]^3.

4- The activation energy for the reaction NO 2 (g)+CO 2 (g)⟶NO(g)+CO(g) is E a = 100kJ/mol and the change in enthalpy for the reaction is ΔH = -200kJ/mol. What is the activation energy for the reverse reaction? Express your answer with the appropriate units.

5- The rate constant of a chemical reaction increased from 0.100 s −1 to 2.60s −1 upon raising the temperature from 25.0 ∘ C to 35.0 ∘ C . Calculate the value of (1 T 2 −1 T 1 ) where T 1 is the initial temperature and T 2 is the final temperature. Express your answer numerically. What is the activation energy of the reaction? Express your answer numerically in kilojoules per mole.

6- According to collision theory, why is the frequency factor not simply the number of collisions between reactants per unit time? Choose from below
because some collisions do not break the important bonds in the reactants
because molecules repel one another when they get too close, thus preventing a reaction
because reactants have to collide in the proper orientation for the reaction to occur
because not all collisions have enough energy to produce a reaction

7- Half-life equation for first-order reactions:
t 1/2 =0.693 k
where t 1/2 is the half-life in seconds (s) , and k is the rate constant in inverse seconds (s −1 ) .

A- What is the rate constant of a first-order reaction that takes 345seconds for the reactant
concentration to drop to half of its initial value? Express your answer with the appropriate units.

B- A certain first-order reaction has a rate constant of 7.80×10−3s −1 . How long will it take for the reactant concentration to drop to 1 8 of its initial value?Express your answer with the appropriate units.

8- What is the difference between the rate law of a reaction and the integrated rate law? Choose from :
The integrated rate law relates reactant concentration to the time elapsed.
Integrated rate laws always produce a linear relationship between reactant concentration and time.
The integrated rate law excludes the rate constant.
The integrated rate law is independent of reaction order.
9- Consider the reaction
5Br − (aq)+BrO − 3 (aq)+6H + (aq)→3Br 2 (aq)+3H 2 O(l)
What is the average rate of consumption of H + during the same time interval?

10- The reaction of compound A forming compound B was studied and the following data were collected:
Time (s )
[A] (M )

0. 0.184
200. 0.129
500. 0.069
800. 0.031
1200. 0.019
1500. 0.016

Part A
What is the average reaction rate between 0. and 1500. s ? Express your answer to three significant figures and include the appropriate units.

Part B
What is the average reaction rate between 200. and 1200.s ?Express your answer to three significant figures and include the appropriate units.

Part C
What is the instantaneous rate of the reaction at t=800. s ?Express your answer to two significant figures and include the appropriate units.

Solution Preview

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Chemical Kenetics
1- Consider the following elementary steps that make up the mechanism of a certain reaction1
1. 3A→B+C
2. B+2D→C+F
2- What is the rate law for step 1 of this reaction? Express your answer in standard MasteringChemistry notation. For example, if the rate law is k[A][C] 3 type k*[A]*[C]^3.
Rate=k[A]^3
3- What is the rate law for step 2 of this reaction?Express your answer in standard MasteringChemistry notation. For example, if the rate law is k[A][C] 3 type k*[A]*[C]^3.
Rate=k[B][D]^2

4- The activation energy for the reaction NO 2 (g)+CO 2 (g)⟶NO(g)+CO(g) is E a = 100kJ/mol and the change in enthalpy for the reaction is ΔH = -200kJ/mol. What is the activation energy for the reverse reaction? Express your answer with the appropriate units.
Activation energy for the reverse reaction: Ea-ΔH=100kJ/mol+200kJ/mol=300 kJ/mol
5- The rate constant of a chemical reaction increased from 0.100 s −1 to 2.60s −1 upon raising the temperature from 25.0 ∘ C to 35.0 ∘ C . Calculate the value of (1 T 2 −1 T 1 ) where T 1 is the initial temperature and T 2 is the final ...

Solution Summary

The solution discusses chemical kenetics.

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