PHENOMA practical book for schools 2019 PHENOMA practical book for schools 2019 | Page 125

Chemistry:
Measure your lung capacity.
When we breathe we expel CO2 that is be able to change the phenolpthalein color
because it has changed the pH. Phenolphthalein is an indicator acid-basic.
The blue bottle.
The prepared mixture is colourless, but if you shake it, it becomes blue. It’s a reac-
tion of glucose oxidation by oxygen in the air. The catalyst is methylene blue.