A decomposition reaction is the breakdown of a compound into two or more components.
- Usually achieved by strong heating of compound.
- To constant weight.
- Gravimetric analysis (change in mass to find composition)
2NaHCO3(s) → CO2(g) + H2O(l) + 2NaCO3(s)
CuSO4.5H2O(s) → CuSO4(s) + 5H2O(l)
- Boiling tube
- Electronic scales
- Clamp stand
- Bunsen burner
- Safety glasses
- Weigh a clean, dry boiling tube, using a balance (accurate to 2 d.p.).
- Record this mass (and all following masses).
- Add about 2 g of compound and reweigh accurately the boiling tube and contents. Record the total mass.
- Clamp boiling tube horizontally then heat boiling tube, gently at first (for a few minutes) and then strongly for 10 minutes turning boiling tube in clamp periodically.
- Allow to cool, reweigh and record the mass.
- Heat strongly for another 5 minutes, cool, reweigh and record the mass again.
- If the mass in step 5 is within 0.05 g of the mass in step 4, use this value for the calculations below. Otherwise, repeat step 5, until two masses within 0.05 g are achieved (constant weight).
Safety glasses should be worn while conducting this experiment. Also try to point boiling tube in direction away from others when heating.