Reactivity 2.2- Kinetics

Question 1

What needs to occur for two reactant particles to react?

Answer 1

1. They need to collide
2. They need to collide with sufficient energy (at or equal to activation energy)
3. They need to collide in the correct orientation

Question 2

What are the factors that influence the rate of a reaction

Answer 2

1. Concentration
2. Pressure
3. Surface area
4. Temperature
5. Catalysts

Question 3

Explain the effect of increasing the concentration of one of the reactants on the frequency of collisions between reactant particles, and thus the rate of reaction.

Answer 3

The higher the concentration of a reactant:
* More reactant particles per unit volume
* More frequent collisions between reactant particles
* More frequent successful collisions resulting in product formation
* Greater rate of reaction

Question 4

Explain the effect of increasing surface area of a solid reactant on the frequency of collisions between reactant particles, and hence, the rate of reaction.

Answer 4

The greater the surface area of a solid reactant:
* More reactant surface exposed to collisions
* More frequent collisions between reactant particles
* More frequent successful collisions resulting in product formation
* An increased rate of reaction

Question 4

If the pressure is increased by decreasing the volume of the reaction vessel, explain the effect on the frequency of collisions between reactant particles, and hence, the rate of reaction.

Answer 4

The higher the pressure resulting from a decrease in volume:
* More reactant particles per unit volume
* Reactant particles collide more frequently with the walls of the container and with particles
* More frequent successful collisions resulting in product formation
* Greater rate of reaction

Question 5

Explain the effect of increasing temperature on the rate of reaction

Answer 5

If the temperature of a reaction mixture is increased:
* The average kinetic energy of the reactant particles increases
* A greater proportion of collisions between reactant particles have energy equal to or greater than the activation energy
* A greater proportion of collisoons are successful
* An increased rate of reaction

AND
* Reactant particles have more kinetic energy
* Reactant particles are moving faster and collide more frequently
* More frequent successful collisions resulting in product formation
* An increased rate of reaction

Question 6

Explain the effect of adding a catalyst on the rate of a reaction

Answer 6

The addition of a catalyst:
* Lowers the activation energy required for a successful collision by providing an alternate reaction pathway
* A greater proportion of collisions between reactant particles have energy equal to or greater than activation energy
* A greater proportion of collisions are successful
* More frequent successful collisions resulting in product formation
* An increased rate of reaction