3rd method (photosynthesis practical)

• What apparatus do we need for this version?

  a conical flask with pondweed inside, bung attached to tube to gas syringe
• 1. Add sodium hydrocarbonate to make sure pondweed as enough carbon dioxide
• Why Is sodium carbonate used?

  it makes sure plant has enough carbon dioxide as it releases oxygen in a solution.
• 2. Place light source 10cm away from pondweed
• 3. Let pondweed to photosynthesis for a set amount of time e.g 1 minute
• 4. As it photosynthesises, the oxygen released will be collected by gas syringe and will allow an accurate measure of volume of oxygen
• 5. Repeat whole experiment with light source 10cm more away from pondweed
• Rate of oxygen production can be calculated as?

  volume produced/ time taken