Topic 5: Kinetics Y1

Question 1

Collision theory

Answer 1

For a reaction to occur the particles must occur in the right orientation and with enough energy (greater than or equal to Ea) to be successful.

Question 2

Axis of Maxwell-Boltzmann distribution

Answer 2

X axis - energy
Y axis - no. molecules (at given energy)

Question 3

Area under curve of M-B distribution

Answer 3

Total no. molecules
Note: no particles touching x axis with zero energy

Question 4

Peak of graph on M-B distribution represents

Answer 4

Most probable energy

Question 5

Shape of curve on M-B distribution with higher temp.

Answer 5

Same area, peaks lower and shifted right (lower number of most probable energy, higher energy of peak), overall flatter with more particles over the Ea line

Question 6

Catalysts

Answer 6

Decrease activation energy by providing an alternate pathway for the reaction to take place.
increases the rate of a chemical reaction without being changed in chemical composition or amount

Question 7

Factors affecting rate of reaction

Answer 7

Temp, conc of solution, pressure, S.A. of solid reactant, presence of a catalyst.

Question 8

Increasing temp affect on rate of reaction

Answer 8

Increases KE of particles, increases speed, increased frequency of successful collisions

Question 9

Increased conc of solution affect on rate of reaction, constant?

Answer 9

More particles present in volume, increased frequency of successful collisions. As time goes on reactants used up so rate of reaction decreases.

Question 10

Increased pressure of gas reaction affect on rate of reaction

Answer 10

More molecules/ atoms in given volume so increased frequency of successful collisions.

Question 11

Increased SA of solid reactants affect on rate of reaction

Answer 11

Increased total surface area of solid, more particles able to collide with others, more sites of reaction increases rate of reaction. (Crushing into powder)

Question 12

Activation energy

Answer 12

The minimum amount of energy that particles require in order for a successful collision to occur which will cause the reaction to happen.

Question 13

Enthalpy profile endothermic reaction

Answer 13

Reactants lower (enthalpy) than products, activation energy is difference between peak and reactants.

Question 14

Enthalpy profile exothermic reaction

Answer 14

Reactants higher (enthalpy) than products, Ea is difference between peak and reactants.

Question 15

Mean energy in M-B distribution

Answer 15

Not the same as most probable, higher energy than it

Question 16

rate of reaction def

Answer 16

The rate of reaction is the speed at which a chemical reaction takes place