CONTROLLING THE RATE

Question 1

Why is it important that chemists can control rate of reaction?

Answer 1

Ensure processes are both economically viable and safe

Question 2

rate of reaction

Answer 2

change in quantity / change in time

Question 3

relative rate

Answer 3

1 / time

Question 4

collision theory

Answer 4

Must collide with enough kinetic energy (to overcome repulsive forces and break bonds between them) and correct geometry

Question 5

minimum kinetic energy for reaction to occur

Answer 5

activation energy

Question 6

Activated complex

Answer 6

An intermediate stage is reached in which a high energy, unstable arrangement of atoms is formed called activated complex

Question 7

Altering factors

Answer 7

temperature
concentration
particle size
use of a catalyst

Question 8

Temperature

Answer 8

increases kinetic energy and so move quicker, increasing temperature increases rate of reaction

Question 9

Concentration

Answer 9

More reactant particles moving closer together - more collisions - so reaction rate increases

Question 10

particle size

Answer 10

decreasing particle size, increases surface area for reaction to take place on

Question 11

catalyst

Answer 11

provide surface for reaction to take place on

reactant molecules are held at favourable angles for geometry to be correct for reaction to occur

decreases activation energy required

Question 12

tempertaure and Ea

Answer 12

move curve right and slighty lower

Question 13

endothermic reaction

Answer 13

heat energy absorbed -products have more enthalpy than reactions

delta positive

Question 14

activated complex in graph

Answer 14

highest point

Question 15

catalyst in graph

Answer 15

lowers curve - Ea

delta H stays same