Unit 6- Kinetics

Question 1

_____ catalyze most reactions that take place in the body.

Answer 1

Enzymes

Question 2

Why are we interested in the rates of reactions?

Answer 2

The rates of the reaction can be used to help determine the mechanism of a reaction, and catalysts allow us to carry out reactions in a more efficient manner.

Question 3

What does the “mechanism” of a reaction mean?

Answer 3

In detailed explanation of how the reactants and catalysts interact to form the product.

Question 4

What do catalysts do specifically?

Answer 4

They lower the activation energy of a reaction.

Question 5

How is a reaction rate illustrated on a graph?

Answer 5

Curves are constructed for the concentration of the reactant and the concentration of the product through the progression of time. The concentrations are obtained from a spectrophotometer and to use the spectrophotometer titrations need to be done.

Question 6

The change in the concentrations of the reactants is highest when and lowest when?

Answer 6

Highest near the beginning and lowest near the end of the reaction.

Question 7

What is a rate expression? what is the basis of it?

Answer 7

General formula for rate determinations

The basis of it is that it is 1 over the moles of reactant times the negative change in concentration of the reactant over time is equivalent to 1 over the moles of product times the + change in concentration of products.

Question 8

Define Rate Laws

Answer 8

They are solely based on the concentration of the reactants.

Question 9

What is the difference between rate laws and rate expressions?

Answer 9

Expressions can be written using both the products and the reactants whereas rate laws can be written only using the concentration of the reactants.

Question 10

How does the increase in the concentration of reactants affect the rate?

Answer 10

With an increased concentration of reactants, the rate will increase (more frequent collisions)

Question 11

_____ are the exponents on the reactants and are determined experimentally.

Answer 11

Rate Orders

Question 12

Why does the initial rate of the reaction provide useful information about how reactants interact in the reaction?

Answer 12

Because the reactants are at high concentration, which means that more frequent collisions are happening. So, from this, we can determine the mechanism of the reaction.

Question 13

What information do reaction orders provide us with?

Answer 13

They provide information for how the reactants behave.

Question 14

Define Transition State

Answer 14

The configuring of atoms act maximum in the potential energy profile.

Question 15

What is the value of the rate constant dependent on?

Answer 15

The temperature and the addition of a catalyst; IT IS NOT DEPENDENT ON THE CONCENTRATION OF REACTANTS.

Question 16

If constant temperature and no catalyst; _____ doesn’t affect k.

Answer 16

Increase in the concentration of reactants.

Question 17

How do you speed up a chemical reaction?

Answer 17

Increasing the temperature leads to the increase in kinetic energy of the molecules, leading to more frequent collisions. So, molecules can reach activation energy. Increasing the concentration of the reactants. Using catalysts to lower the activation energy.

Question 18

Substrates are _____.

Answer 18

Reactants

Question 19

Explain everything about zero order reactions.

Answer 19

The concentration of the reactant does not have an impact on the rate. There is a negative slope on a plot of [] over the course of time.

Question 20

Explain everything about 1st-order reactions

Answer 20

They have a negative slope on a graph with the plot of ln[] over the course of time. The half life of a first order reaction is the .693/k

Question 21

Explain everything about 2nd-order reactions

Answer 21

They have a positive slope for the plot of 1/[] over the course of time. The half life for the second order reaction is 1/k[A]0

Question 22

What is the Collision Theory

Answer 22

As the average kinetic energy increases, the average molecular speed increases, and thus the rates of collisions increases.

Question 23

What was done for the in-class activity?

Answer 23

Used the absorbance + concentration at time 0 to find the molar absorbpivity; then the epsilon and the absorbance value were used to find the concentration at a certain time. Then, ln [] or 1/[] was plotted.

Question 24

How do we know if the reaction is of a certain order based off of the graphs obtained?

Answer 24

Whichever one has a greater R^2 value corresponds to the one that it is supposed to match.

Question 25

What is the unit for K for a zero order reaction and what is the trend as the order increases?

Answer 25

0 ——> Ms^-1; 1 ———> S^-1 ….

An M gets removed as you move upwards.