Bromthymol Blues Lab

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Bromthymol Blues Lab Introduction In this lab our group will demonstrate if carbon dioxide (CO2) is present during photosynthesis and cellular respiration. We will attempt this experiment by using an indicator called bromthymol blue. This indicator will turn yellow if CO2 is present during cellular respiration and during photosynthesis the indicator will turn from yellow to blue if the CO2 has been absorbed by the plant. II. Purpose To demonstrate that CO2 is used during photosynthesis. To demonstrate that CO2 is produced during cellular respiration. III. Hypothesis 1. If we put elodea, bromthymol blue, seltzer water, and regular water in a vial in the sunlight then we can demonstrate that carbon dioxide is used during photosynthesis because the indicator will turn blue. 2. If we put elodea, bromthymol blue, and regular water in a vial in the dark then we can demonstrate that carbon dioxide is produced during cellular respiration. IV. Materials 1. Bromthymol blue 2. Capped vials (Gerber baby food jars) 3. Elodea (aquarium plant) 4. Light and dark areas. V. Procedures 1. Divide into a group of 4 2. Send one person to get two vials 3. Send another person to get 2 healthy green plants of elodea 4. Put 2 elodea in each jar 5. Fill the both jars with water up to ¾ of the jar 6. Get a dropper and suck bromthymol blue into the dropper 7. Fill both jars each with 70 drops of bromthymol bblue 8. Get a different dropper and suck up seltzer water with it 9. Add in 20 drops of seltzer water in only one jar 10. Securely close both jars with their cap 11. Put the jar that has the seltzer water in it in the sunlight 12. Put the jar that just has the elodea, bromthymol blue, and regular water inside a dark
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