OZ - Reaction rates

Question 1

A reaction will only take place between 2 particles if…

Answer 1

They collide in the right direction (they need to be facing each other the right way).

They collide with at least a certain minimum amount of kinetic (movement) energy.

Question 2

What is collision theory?

Answer 2

A reaction will only take place between 2 particles if:

• They collide in the right direction (they need to be facing each other the right way).
• They collide with at least a certain minimum amount of kinetic (movement) energy.

Question 3

What is activation enthalpy?

Answer 3

The minimum amount of kinetic energy particles need to react - to break the bonds to start the reaction.

Question 4

How can rate of reaction be measured?

Answer 4

Volume of gas produced - gas syringe.
Mass change
pH change - making or using up H+.
Clock reaction
Colour change - colorimeter.

Question 5

How does increasing the concentration of the reagent affect the rate of the reaction?

Answer 5

Normally increases it as there are more particles in a given volume so collision frequency increases so the rate increases.

Question 6

How does temperature affect the Boltzmann distribution curve?

Answer 6

Curve shifts right, the peak falls and the curve spreads out.

Question 7

How does increasing the temperature of the reagent affect the rate of the reaction?

Answer 7

Higher temp particles have more kinetic energy, increasing the collision frequency and increasing the proportion of particles with the activation energy needed for the reaction to start (Boltzmann distribution curve).

Question 8

How does increasing the temperature of the reaction change the area under the Boltzmann distribution curve?

Answer 8

Remains the same as the total number of molecules remains the same so the area under each curve must be the same.