3.5 rate

Question 1

What are 3 things that can be observed when a reaction happens?

Answer 1

1) colour change
2) temp change
3) bubbles of gas, effervescence

Question 2

What are two things required for a reaction to happen?

Answer 2

• collisions between reactants
• enough energy to react- activation energy

Question 3

What are 6 factors that affect rate of reaction?

Answer 3

• temperature
• light
• pressure
• concentration
• surface area
• catalyst

Question 4

Discuss activation energy and what two factors does it affect?

Answer 4

temperature and light
an increase in any of these increases the amount of energy for each particle
There will be more particles with the activation energy required to react and rate increases.

Question 5

Discuss collision between reactants and what factors are affected by this?

Answer 5

concentration, pressure and surface area
increase in any of these means more collisions between reactants can occur which increase rate of reaction.

Question 6

how to monitor rate?

Answer 6

measure loss in mass PER UNIT OF TIME
measure volume of gas released
measure pressure increase
measure depth of colour
sampling conc of reactant or product

Question 7

what is sampling?

Answer 7

removal of a small sample on the total solution at intervals

Question 8

what is quenching

Answer 8

placing the sample into iced water to stop the reaction

Question 9

iodine clock experiment

Answer 9

• all solns are kept the same conc except the one being investigated
• several expts with varied conc are carried out and time taken to turn blue/black is recorded
• rate is calculated from 1/time and plotted to establish order of each reactant