3.1.5 Kinetics

Question 1

Collision theory

Answer 1

Most collisions between molecules or other particles do not lead to reactions
Have to have enough energy to overcome the activation energy
And at the correct orientation

Question 2

Factors that effect the rate of reaction

Answer 2

Increase the temperature
Increase the conc
Increases the pressure of a gas reaction
Increase the SA of solid reactions
Use a catalyst

Question 3

Activation energy

Answer 3

The minimum energy needed to start breaking bonds

Question 4

Transition state / activated complex

Answer 4

The species at the top of the curve of an enthalpy diagram
Some bonds are being made and some bonds are being broken

Question 5

Maxwell boltzmann distribution diagram

Answer 5

No particles have zero energy
Most particles have intermediate energy - around the peak
Have very high energy - rhs of the curve (no upper limit)
Average energy and most probable energy not the same
Parcels are all moving a different speeds - energy depends on speed
Area under graph is how many particles

Question 6

Effects of temperature on maxwell boltzmann

Answer 6

Shift to right as more particles have greater or equal to activation energy

Question 7

Substance is heated basic principles

Answer 7

Thermal energy is transferred to the substance
Thermal energy is converted to kinetic energy
Increases particle movement = more collisions
Meaning more successful collisions

Question 8

Concentrations and pressures effect on rate

Answer 8

More molecules in a given volume at higher concs
Means more collisions between molecules as more closely packed together
Meaning successful collisions are more likely

Question 9

Effect of pressure and concentration on maxwell boltzmann

Answer 9

Distribution is shifted to the right

Question 10

Catalysts

Answer 10

Substances that affect the rate of a chemical reaction without being chemically changed themselves at the end of the reaction.
Provide an alternative reaction pathway with a lower activation energy
Do Not effect position of equilibrium or the enthalpy change

Question 11

Catalytic converters

Answer 11

Reduce the level of polluting gas from petrol engines
Zeolite catalysts - ceramic honeycomb covered in platinum and rhodium metals

Question 12

Catalytic converters equation

Answer 12

CO + NO -> N2 + CO2
hydrocarbons + NO -> N2 + CO2

Question 13

Reacts in a catalyst process
(heterolytic)

Answer 13

1. Gases form weak binds with the metal atoms of the catalyst - adsorption
   Holds gases in just the right position for them to react together
2. he products then break away from the metal atoms - desorption
   Freese up room on the catalyst surface for more gases to take place and react