Section 2: Opeu. Response 30. In an investigation, students performed the following steps and made some
observations:
1. The students poured fresh water into a beaker and added a few drops of a
chemical solution called bromthymol blue. The water in the beaker turned blue
2. One student blew through a straw into the water in
the beaker. The water in the beaker turned yellow
3. The students then placed some waterweed (a plant)
into the water
in the beaker and placed the beaker
under a bright light
4. After a short period of time, the students observed
the beaker. The water had turned blue again and
there were bubbles on the waterweed leaves.
The setup of this investigation is shown.
a. The water changed from blue to yellow when the student blew into it (step 2). Identify
the compound that caused the water to change from blue to yellow.
b. Explain why the water turned blue again when the beaker with the waterweed was
under the bright light (step 4). In your explanation, identify the process that caused
this change.
c. Explain why there were bubbles on the waterweed leaves (step 4).
that caused the changes in step 4. You may