3 Using the gracdated cyfinder, measure 20 mi of the BTB solution and pour it in
ID: 210873 • Letter: 3
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3 Using the gracdated cyfinder, measure 20 mi of the BTB solution and pour it into the fask. Record the color of the solution in Table 1 belo Table 1. Color of BTB Solution in Flask Initial Color of BTE BTB Color after Blowing into It Color of BTB Cover the top of the flask with a paper towel so that the liquid won't splash out. Tilt the flask and insert a straw into the deep end of the liquid. Bubble CO, from your exhaled breath into the 20 ml of BTB until a significant color change occurs. (Long, slow exhalations work best.) Record the color of this solution in Table 1 above. 5. Answer the following questions: What is the color of BTB in the presence of an acid? tino . a. at color did BTB turn after you exhaled CO, into it? c. What acid is produced by bubbling CO, into H,0?_tbmic Pour half (10 ml) of the solution in the flask (from step #4) into each of two test tubes. Label one tube "P" for plant, and the other tube "C" for control. Record the color of the solution in each test tube in Table 2 in the Data and Results section 6. below. Insert a clump of the plant, about 1 inch long, into Tube P. Be sure that the plant is completely submerged. Put the tubes in the test tube rack under bright light. (Your 7. instructor will give you directions for the placement of the tubes.) 8. Leave the tubes in the bright light for 45 minutes LAB REPORT: PHOTOSYNTHESIS EXPERIMENT DATA AND RESULTS Table 2. Color of BTB in Test Tubes Initial Color of BTB in Test Tube Final Color of BTB in Test Tube olmo Tube P TY Tube CExplanation / Answer
16) The color change of BTB solution indicates that the carbon dioxide exhaled by breath into test tube can alter the pH changing from alkaline to acidic as the alkaline pH is represnt4ed by the blue/green color whereas the changed green yellow indicates the acidic pH
17) In the tube P most significant change was seen as it was fitted with plant while the control tube which was free from any plant didn’t showed any color change
18) From the above we can estimate that carbon dioxide alters the pH levels and changes the pH from alkaline to acidic which is shown by the color change, when carbon dioxide was exhaled by breath the color was changed to yellow indicating the role of carbon dioxide in pH changes while in the second step when tube was fitted with plant the color was changed from yellow to green indicating the oxygen released from plant influenced the pH and also carbon dioxide was absorbed by the plant.
19) The source of the carbon dioxide for the experiment is the exhaled breath which contains most of carbon dioxide.
20) The color change from the green to yellow indicates that the carbon dioxide was dissolved and changed the color of the solution. If carbon dioxide was liberated there would have been no color change.
21) The carbon dioxide present in the solution was completely absorbed by the plant for the process of photosynthesis hence no carbon dioxide was released in the air but was utilized by the plant thus reducing the carbon dioxide concentration in the plant and changing the pH to alkaline.
22) The variable part was that one tube was fitted with plant and the control was without any plant which caused the variation of the result.
23)a) Bothe the tubes were of acidic solution with yellow color.
b) Bothe the tubes were placed under bright sunlight for same time.
c) Same temperature conditions were maintained.
24) The consumption of carbon dioxide in the experiment was shown by use of plant which by process of photosynthesis took up entire carbon dioxide present in the solution which was indicated by the bromo thymol blue solution.
25) As per theory carbon dioxide reacts with water molecules releasing hydrogen ions in the water and with more free available hydrogen ions the pH changes form alkaline to acidic and same was seen in the experiment. The result also explained this phenomenon.
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