Effect of Temperature

Question 1

why does increasing the temperature increase the rate?

Answer 1

• the particles have more kinetic energy
• so the percentage of collisions with enough energy is higher
• so there are more successful collisions per unit time
• although the particles also collide more often, the effect is not significant

Question 2

how can increasing temperature can be accomplished?

Answer 2

by heating

Question 3

what is the magnesium and acid experiment?

Answer 3

• the effect of temperature on rate can be demonstrated by reacting magnesium with hydrochloric acid

Mg(s) + 2HCl(aq) → MgCl2(aq) + H2(g)

• in this reaction the magnesium disappears

Question 4

what are the variables of the magnesium and acid experiment?

Answer 4

input = the temperature of the HCl (aq)
output = the time taken for Mg (s) to disappear
control:
- mass and surface area of Mg (s)
- volume and concentration of HCl (aq)

Question 5

how is rate calculated from the times taken in the magnesium and acid experiment?

Answer 5

rate (s^-1) = 1/time taken (s)

Question 6

what are the results of the magnesium and acid experiment on a graph?

Answer 6

important conclusions from this graph are:
- its not a straight line - this is because rate isn’t proportional to temperature
- it doesn’t go through the origin - this is because rate isn’t zero at 0 degrees C