Photosynthesis "Dry Lab"

So instead of doing an experiment and writing down the observations, this week we went backwards. We were given a set of observations and we had to write the procedure that went along with this experiment. It was kind of hard for me at first but then I looked at other peoples blogs and that helped me understand. So here is my Photosynthesis "Dry Lab."



Materials

•           Distilled Water
•           Bromothymol Blue (BTB)
•           Aquarium Snail
•           Elodea
•           Large test tubes
•           Light
•           Dark space

        

Procedure

1. Put 15 ml of water and 15 drops of  BTB in a large test tube and let it sit for 3 hours under light. Record your observations.
2. Put 15 ml of water, 15 drops of BTB, and an aquarium snail in a large test tube and let it sit for 3 hours under light. Record your observations.
3. Put 15 ml of water, 15 drops of BTB, and a elodea (funny plant) in a large test tube and let it sit for 3 hours under light. Record your observations.
4. Put 15ml of water, 15 drops of BTB, an aquarium snail, and an elodea in a large test tube in the light for 3 hours. Record your observations.
5. Repeat Step 4 procedure but put it in the dark for three hours and let it sit. Record your observations.

(If your water doesn't turn blue after 15 drops of BTB keep putting drops in until it turns blue)


Observations:
Water plus BTB is blue-green.
         Water is neutral. It changes to the color of the substance that is put in it.


Water plus BTB and an Aquarium Snail is yellow in light.
          Animals respire (breath) and they let Carbon Dioxide out. Carbon dioxide in water produces carbonic acid. When there is acid in BTB and water it turns to yellow.


Water plus BTB plus elodea is blue-green in light.
          Green plants respire. Then they photosynthesize and use the Carbon Dioxide. The plant keeps the water from acid it stays a neutral at the blue green color.


Water plus BTB plus a snail plus elodea is blue-green in light.
          The plant and snail respire. But the plant photosynthesizes and uses the Carbon Dioxide so it turns to blue green and there is no carbonic acid.

Water plus BTB plus a snail plus elodea is yellow in dark.
          The snail and plant respire. Since there is no light the plant can't photosynthesize. The carbon dioxide is still in the water so it stays an acid and the color stays yellow.


Conclusion:
When BTB is added to water it turns yellow because Carbon Dioxide and water mixed together make a carbonic acid. It stays blue with just water because water is a neutral.