3.5 Chemical Kinetics

Question 1

What is the collision theory

Answer 1

Reactants must collide at the correct orientation and with significant energy

Question 2

Factors that affect rate of reaction

Answer 2

Concentration
Pressure
Surface area
Temperature
Catalyst

Question 3

How does a catalyst work

Answer 3

Lowers the activation energy needed for a reaction to begin

Question 4

What is order of reaction

Answer 4

The power to which we have to raise the concentration to fit the rate equation

Question 5

Some methods used to measure rate of reaction

Answer 5

• measure gas volume at constant pressure
• measure gas pressure at constant volume
• measure change in mass
• use of colorimetry
• sampling and quenching

Question 6

What is the overall order of reaction

Answer 6

The sum of the powers of the concentration terms in the rate equation

Question 7

How must orders be found

Answer 7

Experimentally

Question 8

What is k

Answer 8

Rate constant

Question 9

What affects k

Answer 9

Temperature and catalyst

Question 10

What is the unit for rate

Answer 10

Moldm-3s-1

Question 11

What to look for when working out rate data

Answer 11

Find 2 sets of data where only 1 concentration changes

Question 12

What is the reaction mechanism

Answer 12

The steps that must occur during a chemical reaction

Question 13

What is the rate determining step

Answer 13

The rate of the slowest step that limits the overall rate of reaction

Question 14

What does it mean if the concentration of a reactant appears in the rate equation

Answer 14

The reactants or something derived from it takes place in the rate determining step

Question 15

State the Arrhenius equation

Answer 15

K= Ae^-Ea/RT

Question 16

Units for activation energy in the Arrhenius equation is

Answer 16

Jmol-1

Question 17

What is the effect of a catalyst on the Arrhenius equation

Answer 17

It will lower the activation energy
This will cause the value of e to increase and so the value of K will increase

Question 18

What can entropy be described as

Answer 18

A measure of disorder
Or
The amount of randomness in a system
Or
The dispersal of energy

Question 19

What is the symbol for entropy

Answer 19

S

Question 20

Greater entropy means

Answer 20

More disorder

Question 21

Put solid, liquid, gas in order of increasing entropy

Answer 21

Solid<liquid<gas

Question 22

How to calculate the entropy change from absolute entropy values

Answer 22

/\S = Sfinal - Sinitial

Question 23

What is standard entropy

Answer 23

The entropy contents of one mole of that substance under standard conditions

Question 24

Units for stanard entropy

Answer 24

Jk-1mol-1

Question 25

What does Gibbs free energy do

Answer 25

Combines entropy and enthalpy to decide if a reaction is feasible or not

Question 26

How to calculate gibs free energy

Answer 26

/\G=/\H - T/\S

Question 27

What does it mean if gibbs free energy is negative

Answer 27

The reaction is feasible and can occur spontaneously

Question 28

What does it mean is gibbs free energy is positive

Answer 28

At that temperature the reaction is not feasible and cannot occur spontaneously

Question 29

What is the value of /\G at the temperature that the reaction begins to be possible

Answer 29

0

Question 30

How to calculate the temperature that a reaction begins to be possible

Answer 30

T = /\H / /\S

Question 31

What is the value of /\G when the system is at equilibrium

Answer 31

0