Rates Of Reaction

Question 1

What is rate of reaction

Answer 1

1. Increase in concentration of a product per unit time
2. The decrease in concentration of a reactant per unit time

Rate = change in concentration/ change in time

Question 2

Why does the average rate decrease as the reaction proceeds

Answer 2

As the reaction rate proceeds there are fewer collision between reactants and molecules

Question 3

What is a zero order reaction

Answer 3

Rate is unaffected by changing the concentration of a given reactant

Question 4

What is a first order reactant

Answer 4

Changing the concentration has the same affect on the rate of reaction , if concentration doubles rate doubles

Question 5

What is a second order reactant

Answer 5

Changing the concentration has squared the effect on the rate of reaction

Question 6

How can concentration time graphs be used to determine order

Answer 6

Zero order
- straight line
- detracting half life

First order
- constant half life
- units s^-1

Second order
Increasing half life
- units mol^-1dm^3s^-1

Question 7

How can rate concentration graphs by used

Answer 7

Zero order
- horizontal line

First order
- rising straight line

Second order
- upwards curve

Question 8

What is half life

Answer 8

Time taken for the concentration of the reactant to reduce by half

K= ln2/ half life

Question 9

What affects the rate constant and how

Answer 9

• increase in temperature increases k
• addition of a catalyst increases k

Question 10

Basic rate equation

Answer 10

Rate = k [x] ^a [y]^b

Question 11

Explains what happens when a catalyst is added in terms of K

Answer 11

When a catalyst is added Ea becomes smaller so e^-eA/RT becomes larger and rate increases