Unit 5-Kinetics

Question 1

Collision theory

Answer 1

• reactions are just energetic collisions between reactant particles, taking place in the correct direction and with sufficient energy to cause a reaction
• particles must react with a required activation energy to be successful
• can be affected by he concentration, pressure, temperature and surface area of reactants
• catalysts lower the required energy for a successful collision

Question 2

Catalysts

Answer 2

• Provide alternative pathways for reactions to increase rates of reaction
• always end the reaction as they started without being used up
• sometimes only work for single reactions

Question 3

Reaction rates

Answer 3

• rate=amount of reactant used or product formed÷time taken
• can measure time for precipitate to form, change in mass or volume of has produced to work out how much product was formed, reactant was used
• higher temperature will increase the average distribution of energy, so more particles with have energy greater than activation energy and rate will increase

Question 4

Effect of concentration and pressure

Answer 4

• increasing concentration forces more reactant particles to be closer together so rate increases
• increasing pressure has the same effect on gasses and increases collision frequency