1. C2.19 Speeding up reactions- Temperature
The heat is on
Sunday, 23 April 2017
C2.19 Speeding up reactions- Temperature
LO: Explain reaction rates in terms of particles and how temperature affects this
Starter: Imagine you have a jelly baby
Your task is to dissolve this in water faster than anyone else in the room.
How will you do this?
Write your method down in your book
Please put your bags & coats away

2. Objectives Define activation energy.
Describe the effect of changing temperature on the rate of reaction.
Explain the effect of changing temperature on the rate of reaction.

3. A brief background
Reactions take place when particles collide with a certain amount of energy.
The minimum amount of energy needed for the particles to react is called the activation energy and is different for each reaction.
In your own words write a definition of activation energy – 3 minutes
Activation energy – the minimum amount of energy particles must have to react

4. Objectives Define activation energy.
Describe the effect of changing temperature on the rate of reaction.
Explain the effect of changing temperature on the rate of reaction.

5. Collision theory
The energy of collisions and the frequency (how often) affect the rate of reaction
We are going to investigate how temperature affects this.

6. 2Mg + 2HCl MgCl + H2
Investigating how temperature affects reaction rate between magnesium ribbon and hydrochloric acid.
Answer these questions in your book:
What is the dependent varible?
What is the independent varible?
3. Which varibles must be kept constant?

7. Wear your goggles Method 1. Collect equipment listed on sheet
Goggles & tidy work space
Cold Hcl
Hot Hcl
Room temp. Hcl
3 cm Magnesium ribbon
Wear your goggles
 Method
1. Collect equipment listed on sheet
2. Measure out 10 cm3 of cold hydrochloric acid
3. Take temperature and record it in the table below
4. Add a strip of magnesium and start timer
5. Stop clock when all magnesium has reacted
6. Record results in table
7. Repeat steps 2-6 for room temperature acid and warm acid
8. Tidy away
9. Stick your sheet in your book

8. Method Measure out 10cm3 of chilled HCl into a boiling tube
Take the temperature and record it
Add 3cm length of Mg ribbon and start stop watch,
Record how long it takes for the Mg to be used up and record it in the table
Repeat using room temperature and then warm acid

9. Copy and complete
Our fastest reaction was __________ Our slowest reaction was __________ Our investigation showed that as temperature increased the rate of reaction __________________

10. Objectives Define activation energy.
Describe the effect of changing temperature on the rate of reaction.
Explain the effect of changing temperature on the rate of reaction.

11. Explaining the effect of temperature
So how can we explain this in terms of particles?
Particle temperature animation
What happens when the temperature is increased?
WHAT WILL THIS DO TO COLLISIONS?
2 minutes in pairs to explain FULLY

12. SUMMING UP
Increasing the temperature increases how often particles collide (frequency of collision) AND how much energy they collide with
This means there are far more successful collisions every second = faster rate of reaction

13. COMPLETE THE WORKSHEET YOU HAVE 5 MINUTES
Objectives
Define activation energy.
Describe the effect of changing temperature on the rate of reaction.
Explain the effect of changing temperature on the rate of reaction.
PROVE IT
COMPLETE THE WORKSHEET YOU HAVE 5 MINUTES

14. What happens if particles collide with less energy than the activation energy?
2.Describe what happens to the rate of reaction when the temperature is decreased. C
3. Use the graph to answer these questions;
Explain in terms of particle why the rate of reaction doubles between 60C and 80C.
Estimate the rate of
reaction at 30C. A*

15. C2.19
1. Nothing / no reaction
2. The colder the slower/ it gets slower / slows down
3. a) The particles move faster at 80 (deg) that they do at 60 (deg), there are more frequent collisions at the higher temperature, the collisions are more energetic, and so more likely to be successful.
b) About 36 s

16. COMPLETE THE WORKSHEET YOU HAVE 5 MINUTES
Objectives
Define activation energy.
Describe the effect of changing temperature on the rate of reaction.
Explain the effect of changing temperature on the rate of reaction.
PROVE IT
COMPLETE THE WORKSHEET YOU HAVE 5 MINUTES