1. Kinetics - experiment Starter…
Hydrogen peroxide (H2O2) decomposes in the presence of manganese(IV) dioxide to form water and oxygen gas in a first order manner with respect to H2O2.
Write a balanced symbol equation.
What method would you use to measure the rate?
If the initial concentration of H2O2 was 0.98 mol dm-3 and 20cm3 of O2 was given off. What is the concentration of H2O2 after 20s?
Sketch the expected time/conc and conc/rate graphs.
Review question maybe using a mind map on a white board

2. 5 week plan single lessons
Week 1 – Measuring rates and orders
Week 2 – Initial rates method
Week 3 – Rate equation
Week 4 – Review of papers
Week 5 – Rates CPAC
If you miss a session you MUST download the PowerPoint from the shared area and collect associated materials, this is your responsibility.
You must complete all homeworks or you will not be allowed onto Y13 chemistry. No excuses

3. Decomposition of H2O2 2H2O2(aq)  2H2O(l) + O2(g)
Gas collection method.
2H2O2(aq)  2H2O(l) + O2(g)
O2 n = 20cm3 / 24,000 cm3mol-1
O2 n = mol
H2O2 n 20s = mol dm-3 x 2 =
[H2O2] 20s = ( /5cm3) x1000
= mol dm-3
[H2O2]ini - 20s = 0.98 – = mol dm-3

4. Task
Your task is to confirm that the reaction is first order with respect to H2O2 by using one of two methods.
Method 1
Set up the experiment as shown by your teacher.
Place 5cm3 of 0.98M H2O2 into the flask and connect the collection hose.
Add a small amount of MnO2 catalyst ensuring that the stopper is replaced quickly.
Time how long it takes for 40cm3 of O2 to be collected.
Repeat with 1.96M, 2.94M and 3.96M
Method 2
Set up the experiment as shown by your teacher.
Place 5cm3 of 1.96M H2O2 into the flask and connect the collection hose.
Add a small amount of MnO2 catalyst ensuring that the stopper is replaced quickly.
Record the volume of O2 every 10s until 40cm3 is collected
Repeat 2x more.

5. Tables
Your task is to confirm that the reaction is first order with respect to H2O2 by using one of two methods.
Method 2
Method 1
Time
(s)
vol O2
(cm3)
[H2O2]
(mol dm-3)
Rate
([H2O2] s-1) 10 20 30 40 50
[H2O2]
(mol dm-3)
Time
(s)
rate
(s-1)
0.98
1.96
2.94
3.92

6. Processing Use the excel file to process your results. Method 1
Plot a graph of time vs concentration.
Use the half life method to calculate the order.
Calculate 1/t to get the rate.
Plot concentration vs rate.
Use the shape to determine the order.
Method 2
Plot a graph of time vs concentration.
Use the half life method to calculate the order.
Calculate the gradient every 10 seconds
Plot concentration vs rate.
Use the shape to determine the order.