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Question 1

what is meant by rate of reaction?

Answer 1

change in concentration of a reactant or a product in a given time

Question 2

write an equation for the rate of reaction

Answer 2

rate= change in concentration/ time

Question 3

what as the units for the rate of reaction?

Answer 3

moldm⁻³s⁻¹

Question 4

state 5 factors that can affect the rate of reaction.

Answer 4

• concentration
• pressure
• catalyst
• temperature
• surface area

Question 5

why are some collisions effective?

Answer 5

• correct orientation

- sufficient energy to overcome activation energy

Question 6

how does increasing the concentration affect the rate of reaction?

Answer 6

• increases the number of particles in the same volume
• collide more frequently and closer together
• increases the rate of reaction

Question 7

how does increasing the pressure of a gas affect the rate of reaction?

Answer 7

• the same number of particles but in a smaller volume
• closer together and collide more frequently
• increases the rate of reaction

Question 8

2 methods of measuring progress of a chemical reaction

Answer 8

• monitoring the removal (decrease in concentration) of a reactant
• following the formation (increase in concentration) of a product

Question 9

state 2 possible methods for monitoring the rate of reactions that produce gases

Answer 9

• monitoring the volume of gas produced at regular time intervals using gas collection
• monitoring the loss of reactants using a balance

Question 10

what is a catalyst?

Answer 10

alters the rate of reaction without being used up

Question 11

what effect does a catalyst have on the rate of a reaction?

Answer 11

• speeds up a reaction
• provides an alternative route
• catalyst is regenerated
• catalyst may react with a reactant to form an intermediate

Question 12

complete an enthalpy profile diagram of an exothermic reaction, with and without a catalyst

Answer 12

see page 149

Question 13

complete an enthalpy profile diagram of an endothermic reaction, with and without a catalyst

Answer 13

see page 149

Question 14

what is a homogenous catalyst?

Answer 14

same physical state as the reactants

Question 15

give 2 examples of homogenous catalysts with equations

Answer 15

• making esters with H₂SO₄
  C₂H₅OH(l) + CH₃COOH(l)→ CH₃COOC₂H₅(l) + H₂O (l)
• ozone depletion with Cl• (g)
  2O₃ (g) → 3O₂ (g)

Question 16

what is a heterogeneous catalysts?

Answer 16

different physical state from the reactants

Question 17

give 2 examples of heterogeneous catalysts with equations

Answer 17

• making ammonia (Haber process) with Fe(s)
  N₂ (g) +3H₂ (g) →2NH₃ (g)
• making SO₃ (g) (contact process) with V₂O₅ (s)
  2SO₂ (g) + O₂ (g) → 2SO₃ (g)

Question 18

why do catalysts have great economic importance and benefits?

Answer 18

increased sustainability by lowering temperatures and reducing energy demand from combustion of fossil fuels with resulting reduction in CO₂ emissions

Question 19

the effect of temperature on the Boltzmann distribution

Answer 19

• area under curve exceeding Ea = number of molecules that can react
• at higher temperature, area under curve > Ea is greater so more can react

Question 20

State two characteristics of a dynamic equilibrium.

Answer 20

• rate of forward reaction= rate of reverse reaction

- concentrations of reactants and products do not change

Question 21

le Chatelier’s principle

Answer 21

when a system in equilibrium is subjected to an external change the system readjusts itself to minimise the effects of that change