Topic 7: Rate Of Reaction

Question 1

Factors that increase ROR

Answer 1

• temperature
• concentration of solutions
• pressure of gases
• surface area of solids
• presence of a catalyst

Question 2

How does temperature increase increase ROR?

Answer 2

• Increase in average KE of particles, thus increase in frequency of collisions
• increase in number of successful collisions over time. Thus increasing frequency of successful collisions. Increase ROR
• increase of particles moving at minimum Ea, less energy is required for a successful collision. Increase ROR

Question 3

How does increase concentration of solutions increase ROR?

Answer 3

• more particles in a given volume
• increase number of collisions and increase in the number of successful collisions over time.(increase frequency of successful collisions)
• therefore increase ROR

Question 4

How does increasing the pressure of gases increase the ROR?

Answer 4

• increase in pressure of gaseous reactants means more particles become closer in a given volume.
• increase in number of collisions thus increase in number of successful collisions over time.
• increase in frequency of successful collisions therefore increases ROR

Question 5

How does increasing the SA increase ROR?

Answer 5

• more particles available at the surface to react
• greater number of exposed particles=increase number of collisions over time.
• increase number of successful collisions over time. Thus increasing frequency of successful collisions. Thus increasing ROR

Question 6

How does adding a catalyst increase ROR?

Answer 6

• provides an alternative pathway with a lower Ea.
• increase proportion of particles moving with Ea
• increase the percentage of successful collisions. Thus increase the ROR.

Question 7

What is a catalyst?

Answer 7

• specific elements or compounds that speed of chemical reactions.
• not consumed in the in the reaction. Doesn’t appear as a reactant or product
• affect the forward and reverse reaction

Question 8

What is a homogenous catalyst?

Answer 8

Same state as the reactants and products

Question 9

What is a heterogenous catalyst?

Answer 9

Different phase to the reactants

Question 10

Benefits of using a catalyst

Answer 10

• less energy is required to break reacting bonds so high-speed collisions are not essential.
• The particles are held in position for the reaction
• The reaction can proceed faster or a lower more economical temperature can be used
• The greater the catalyst surface area the larger amount of adult adsorption possible