Photosynthesis Dry Lab

In this lab I had to do everything different. We didn't have to read procedures then do the lab but instead write up the procedures, purpose, and materials because we already have all the data from the lab. This lab is a little different from all the other ones we have done so far this semester.

  

Purpose:

So the purpose of this lab is to detect the effects of the color change of Bromothymol with the different conditions. Four different conditions are being used to test how carbon dioxide may change the color of the BTB when the two are combined.

Background Facts:

• Carbon dioxide in water produces carbonic acid.
• Bromothymol Blue (BTB) is a blue-green liquid which changes to a yellow color in acid and back to blue-green when returned to a neutral pH.
• Carbon dioxide plus water yields sugar and oxygen when chlorophyll and sunlight are present.
• Animals respire.
• Green plants photosynthesize in the light and respire all the time.
• Sugar plus oxygen yields carbon dioxide plus water and energy.

 

Hypothesis:

If you put a fish in the bromothymol blue, then the color is going to change because the two compounds are going to mix.

 

Materials

• 4 Large Beakers
• Bromothymol (BTB)
• 2 Goldfish
• 1 Light
• Aquarium Plant

 

 

Procedures:

1. Label each of the beakers with the numbers 1, 2, 3 and 4.
2.  Fill all four beakers with 500 mL of water.
3. Put 50 drops of bromothymol in each of the beakers
4. Don't place anything in beakers 1
5. Place 1 goldfish in beaker 2
6. Put an aquarium plant in beaker 3
7. Add an aquarium plant and goldfish in beaker 4
8. Now leave the beakers 1, 2 and 3 in constant light for a 24 hour period
9. When the 24 hours is up, record each of the colors.
10. Last leave beaker 4 in the light for 21 hours, record the color
11. Then leave it in the dark for 3 hours, then record the color again.

 

 

Observation:

 

1. Water plus bromothymol blue is blue-green.
2. Water plus bromothymol blue plus an aquarium snail turns yellow.
3. Water plus bromothymol blue plus Elodea (an aquarium plant) is blue-green in light.
4. Water plus bromothymol blue plus a snail plus Elodea is blue-green in light and yellow when left in the dark for three hours.

 

Conclusion/Analysis:

1. Water plus bromothymol blue is blue-green because the BTB starts as a blue-green, but when it is mixed with the water it turns the water blue-green. The mixture stops the oxygen and the sugar from being taken out.
2. Water plus bromothymol blue plus an aquarium snail turns yellow because when the fish breathes in carbon dioxide, the carbon dioxide mixes with the water and it turns to carbonic acid. So when BTB is mixed with an acid, the color changes to yellow until a neutral ph is back into the BTB.
3. Water plus bromothymol blue plus Elodea (an aquarium plant) is blue-green in light because the plant actually takes in all of the carbon dioxide, so in the end the water and BTB will not change color.
4. Water plus bromothymol blue plus a goldfish plus Elodea is blue-green in light and yellow when left in the dark for three hours because carbon dioxide + water slows down sugar and oxygen when chlorophyll and sunlight are present.