Solution (5 cc), the length of pond weed(5 cm)
Apparatus:
7 boiling tubes, 7 rubber stopper, 1 black paper, capillary tube, lamp
Materials:
Pond weed, fresh sodium bicarbonate indicator
Method:
-
CO2 was blown into some fresh bicarbonate indicator until it turns to red, which used for experiment.
- The test tubes are set up like in the diagram 1 and placed at varying distances from the light source. For the control experiment, put in a dark place with no light.
- The time taken for bicarbonate indicator in each test tube to turn from deep red to purple is taken and recorded.
Precautions:
- Make sure that the carbon dioxide blown into the indicator is constant
- The boiling tube must be closed immediately after the pong weed is inserted and the time is taken once the weed is in contact with the indicator
Data collection:
Data processing:
From the experiment, there are no data that can be taken because there are no changes of colour on the bicarbonate indicator. There fore the experiment can be called a failure. Theoretically, the colour of the indicator should turn back from deep red to purple meaning there is oxygen released by the process of photosynthesis. But throughout the experiment, no changes happen to the indicator.
For the controlled experiment, there are no changes of colour recorded; this is because without light, the light–dependent reaction of photosynthesis could not happen thus no oxygen is released.
Oxygen is the substance that changes the colour of the bicarbonate indicator from deep red colour to purple
Evaluation:
From doing this experiment, some flaws that have altered the experiments result has been detected.
- The length of the pondweed is insufficient. Therefore, the amount of oxygen released is not sufficient.
- The time allocated for the experiment to be done is not sufficient. The amount of oxygen released is not sufficient to change the colour of the sodium bicarbonate indicator.
- The volume of the indicator used is too high making the change of colour difficult because there are more mole per cc that is needed to be reacted
- There is other source of light at the place of the experiment making the variable is questionable.
To improve this experiment, some action must be done to make the experiment a lot more accurate the next time it is done:
- The length of the pondweed must be increased but it must have almost the same amount of leaf to ensure that it is one of the fixed variables. The amount of oxygen released will alternately increased therefore the experiments results will be much faster and the data can be taken in time
- The time for doing the experiment should be increased so that there is enough time for the weed to released enough oxygen that will turn the indicator from deep red to purple.
- The volume of the indicator should be decreased so that the colour changes of the indicator will be faster. The concentration of the indicator should also be reduced so that the colour changes would be faster due to the fact that the mole of the indicator is lesser than usual
- The experiment should be done in a very dark place where there are no source of light because the present of other light source will alter the experiment’s results
Conclusion:
The experiment was a failure so no data can be obtained. Therefore a conclusion cannot be done. Theoretically, the indicator will changes colour from deep red to purple because the process of photosynthesis. This process is theoretically said to be affected by the intensity of light.
