Snail and Elodea Lab Bromothymol blue Bromothymol blue

Snail and Elodea Lab

Bromothymol blue • Bromothymol blue (BTB) is a p. H indicator • It is normally blue but turns yellow when the p. H lowers • Carbon dioxide has a p. H of 5. 7 • When carbon dioxide is present the color will change from blue to yellow • Oxygen has a p. H of 6. 7 • When oxygen is present there will be no color change

Set up

Set up • Tube 1= water + BTB • Tube 2= water + snail + BTB • Tube 3= water + elodea + BTB • Tube 4= water +snail + elodea + BTB

Set up Oxygen Carbon dioxide Photosynthesis- Carbon dioxide + water + light glucose + oxygen Respiration- Glucose + oxygen carbon dioxide + water + ATP REMEMBER! Plants do BOTH photosynthesis and respiration

Interpreting Color Change • Blue • Yellow • Green no change or oxygen present carbon dioxide + oxygen present Photosynthesis- Carbon dioxide + water + light glucose + oxygen Respiration- Glucose + oxygen carbon dioxide + water + ATP

Set up • Tube 1= water + BTB • Tube 2= water + snail + BTB • Tube 3= water + elodea + BTB • Tube 4= water +snail + elodea + BTB

Explanation • Tube #1= blue, no CO 2 present • Tube #2= yellow, CO 2 present • Tube #3= blue, no CO 2 present, plant making oxygen • Tube #4= green, CO 2 and oxygen present