What is the role of Bromothymol blue in the Elodea lab?
This lab involves the qualitative measurement of the changes in carbon dioxide concentration associated with respiration and photosynthesis in the freshwater plant Elodea. Bromthymol blue is used as an indicator for the presence of CO2 in solution. When CO2 dissolves in water, carbonic acid is formed.
What Colour does Bromothymol blue turn in a base?
Bromothymol blue has a blue color when in basic conditions (pH over 7), a green color in neutral conditions (pH of 7), and a yellow color in acidic conditions (pH under 7).
What happens to Elodea in the dark?
The Elodea vial placed in the dark lacked light, so photosynthesis did not occur and DO levels would expect to decrease as respiration occurs. The process of respiration requires oxygen and glucose. This process produces CO₂, water (H₂O) and energy (ATP).
What is the reason for the color change in the test tube with elodea submerged in BTB solution?
Bromothymol blue solution, BTB, can indicate the presence of carbon dioxide in the water. When little or no carbon dioxide is present, BTB will show a blue color. Depending upon the amount of carbon dioxide, BTB will change to green or yellow. Yellow indicates more carbon dioxide.
Why elodea is used for photosynthesis experiment?
This North American pondweed is widely recommended for demonstrating oxygen formation during photosynthesis. Elodea is cheap and easy to grow, but other pondweeds can also be used.
Why is Elodea water blue?
As the Elodea absorbs carbon dioxide from the pre-prepared solution, the pH changes cause the colour to change. This change will be observable within 30 minutes to an hour. Bromothymol turns blue when exposed to alkaline (basic) conditions, and yellow-green in acidic conditions; making it an excellent pH indicator.
Why is Elodea used in photosynthesis experiment?
What color does a base turn phenolphthalein?
Phenolphthalein is an indicator — a chemical which changes colour depending on whether it meets an acid or a base. It turns purple if it meets something basic, such as ammonia; it stays colourless if it meets an acid like vinegar or a neutral substance like water.
What do phenolphthalein bases do?
Phenolphthalein is often used as an indicator in acid–base titrations. For this application, it turns colorless in acidic solutions and pink in basic solutions. It belongs to the class of dyes known as phthalein dyes.
Why did the Elodea turn blue?
Why did the tube with Elodea change to a light blue?
We stuffed the elodea plant into one tube and put it in front of the light. carbon dioxide is absorbed from water by the plant in presence of light. The absorption of Co2 from water by the elodea in light is revealed through the change in color of the bromothymol blue from blue to green.
How to make Elodea with bromthymol blue?
Procedure: Pour 75 mL of water into a 250 mL beaker. Add 2 mL of bromothymol blue to the water. It should be a blue solution. Using a straw, GENTLY blow into the solution causing it to bubble for approximately 1 minute. Label 3 large test tubes: 1, 2, & 3 Tube 1 will be the control (no Elodea) Tube 2 will be the Elodea in the dark
How to make bromothymol blue in photosynthesis lab?
Pour 25 mL of the bromothymol blue + water solution into each of the three test tubes. Cover Tube 1 with tin foil (there is no Elodea in Tube 1) and place it in the test tube rack Add a 7 cm piece of Elodea to Tube 2. Using your straw, GENTLY push the Elodea to the bottom of the test tube.
How can I test bromthymol blue in water?
If concentrated bromothymol blue (BTB liquid) is available, dilute with water (distilled works best) and test the concentration by adding 10 ml of your BTB solution to 15 ml water and bubbling one lung full of air through a straw into the water. It should turn greenish.
How to make Elodea in a photosynthesis lab?
Cover Tube 1 with tin foil (there is no Elodea in Tube 1) and place it in the test tube rack Add a 7 cm piece of Elodea to Tube 2. Using your straw, GENTLY push the Elodea to the bottom of the test tube. Then cover Tube 2 with tinfoil and place it in the test tube rack.