Unit 3.4.1 - Kinetics

Question 1

What is the rate of reaction?

Answer 1

The change in the amount of reactants or products per unit time

Question 2

In a graph thats hows the amount of reactants or products against time what shows the rate of reactions?

Answer 2

The gradient

Question 3

Does the rate of reaction increase with a larger or smaller surface area? And why?

Answer 3

Larger - there are more collisions so the reaction happens faster

Question 4

What is the general rate equation for this equation: A + B → C + D ?

Answer 4

Rate = k[A]ᵐ[B]ⁿ

Question 5

What does [A] mean?

Answer 5

The concentration of A

Question 6

What does m stand for in: Rate = k[A]ᵐ[B]ⁿ?

Answer 6

The order of the reaction in respect to the concentration of A

Question 7

What does the order of reaction with respect to a given reactant mean?

Answer 7

How that reactants concentration affects the rate of reaction

Question 8

What is the overall order of a reaction?

Answer 8

The sum of all the powers in the rate equation

Question 9

What does the k stand for in: Rate = k[A]ᵐ[B]ⁿ? And what does it mean?

Answer 9

The rate constant - the constant of proportionality in the rate equation

Question 10

What does it mean if the order is 0?

Answer 10

The concentration of the reactants has no effect on the rate of reaction

Question 11

What does it mean if the order is 1?

Answer 11

The rate of reaction is proportional to the concentration of the reactants

Question 12

If the concentration of a reactant triples how does that affect the rate of reaction is the order to that reactant is 1?

Answer 12

The rate of reaction is three times faster

Question 13

What does it mean if the order is 2?

Answer 13

The rate of reaction is proportional to the concentration of the reactants squared

Question 14

If the concentration of a reactant triples how does that affect the rate of reaction is the order to that reactant is 0?

Answer 14

The rate of reaction remains the same

Question 15

If the concentration of a reactant triples how does that affect the rate of reaction is the order to that reactant is 3?

Answer 15

The rate of reaction is 3² = 9 times faster

Question 16

Does the rate of reaction increase when k increases or decreases?

Answer 16

Increases

Question 17

What affects k? And how?

Answer 17

Temperature - as temperature increases so does k

Question 18

Does k change when concentration and pressure changes?

Answer 18

No

Question 19

What is the initial rate of reaction?

Answer 19

The rate right at the start of the reaction

Question 20

What can you find out by doing the initial rate method?

Answer 20

The order of the reaction in respect to different reactants

Question 21

Describe the initial rate method in 4 steps.

Answer 21

1. ) do an experiment measuring the amount of reactant or product over time
2. ) repeat with different concentrations of the the reactants
3. ) calculate the initial rates from the graphs of each experiment
4. ) then you can see how the concentrations affect the initial rate and so you can find the orders of the reaction

Question 22

If a reaction has a series of steps what is the rate of reaction determined by?

Answer 22

The step with the slowest rate of reaction

Question 23

The step with the slowest rate of reaction in a reaction that involves a series of steps is called?

Answer 23

The rate determining step

Question 24

How can you use the rate equation to help find out which is the rate determining step?

Answer 24

If a reactant appears in the rate equation, then it or something derived from it must be in the rate determining step, if its not in the rate equation then it won’t be in the rate determining step

Question 25

How do you know something is a catalyst from the rate equation?

Answer 25

It appears in the rate equation but not in the overall equation

Question 26

What else does the rate equation show in relation to the rate determining step?

Answer 26

The number of molecules of each reactant in the rate determine step, if its second order then there will be two molecules

Question 27

What does a graph of k against temperature look like?

Answer 27

Question 28

What do the graphs look like for concentraion aginst rate of reaction for 0, 1^st, 2^nd look like?

Answer 28