The peroxide experiment
Hydrogen peroxide decomposes on its own into water and oxygen — but very slowly. What happens when a catalyst is added to it?
Activity 17.4
You will need: two test tubes, a fresh hydrogen peroxide (H2O2) solution, 0.2 g of manganese dioxide (MnO2).
- Put equal volumes of the fresh hydrogen peroxide solution into the two test tubes.
- Into one of them put about 0.2 g of manganese dioxide, weighed accurately.
- Observe the speed at which gas bubbles leave the two tubes.
- At the end of the reaction, filter the solution the MnO2 went into, dry the residue and weigh it again.
hydrogen peroxide → water + oxygen
2H2O2(aq) → 2H2O(l) + O2(g)
The observation
In the test tube holding the manganese dioxide the gas bubbles come off faster. The manganese dioxide has caused the rate of this reaction to increase.
The second half of the definition, though, is still unproven. For that we need the last step — weighing the residue.