Hypothesis: Plants can photosynthesis in a slightly acidic medium.
Approach : Put 2 teaspoon of sodium hydrogen carbonate in each beaker. Put hydrochloric acid in beaker labelled acid and put sodium hydroxide in beaker labelled alkaline. Place 1 hydrilla in each beaker and submerged it fully.
Apparatus:
- 3 beakers
- 3 oxygen censors
- 1 data logger
Materials:
- 2 plastic teaspoons
- hydrochloric acid
- sodium hydroxide
- 2 pH indicator strips
- sodium hydrogen carbonate
- 3 hydrillas
Variables:
Constant: Amount of water, number of hydrilla in each beaker and the type of beaker.
Changing: Type of water (acid, alkaline, neutral)
Measurable: Amount of oxygen released.
Procedures :
- Prepare 3 beakers filled with three quarter of water.
- Label the beakers (acid,alkaline,neutral)
- Drip dilute hydrochloric acid into the beaker labelled acid and measure and ensures its pH value is 2.
- Drip dilute sodium hydroxide into the beaker labelled alkaline and measure and ensures its ph value is 11.
- Put 2 teaspoons of sodium hydrogen carbonate into each beakers.
- Place 1 hydrilla into each beaker and ensure that it is fully submerged.
- Put them under the light for 10 minutes and measure the amount of oxygen in every 5 minutes intervals.
- Record the amount of oxygen released every 5 minutes interval for the 3 beakers.
Results:
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photos : After ten minutes and after 5 minutes.
Discussion:
We realised that there are experimental errors as in theory through research, the optimum pH for hydrilla is between 5.6 and 6.2 and that pH of 3 may kill the hydrilla but our results showed that the more acidic it is the higher the rate of photosynthesis.
Further discussions :
- Determine how much hydrochloric acid and sodium hydroxide solution at first.
- Prepare enough time to do the experiment.
Conclusion:
Therefore in water of pH value between 5.6 and 6.2, the rate of photosynthesis is the highest for hydrilla.
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