Our second Chemistry minilab consisted of testing three white powders–cornstarch, baking powder, and baking soda– by mixing each one with iodine, water, and vinegar.
It was near impossible to determine which powder was which just by looking at them, but subjecting each of them to different liquids and observing their reactions would still be an easy way to determine which was which. Well, we did just that and here were the results of the nine combinations:
1. Baking soda, Iodine: Baking soda absorbed iodine, though not completely. Had an orange, iodine-colored color.
2. BS, Water: Water is absorbed a bit; turns cloudy/opaque.
3. BS, Vinegar: Fizzes a lot, doesn’t completely dissolve, and leaves a white residue.
4. Baking Powder, I: Turns very black-colored, doesn’t dissolve much, turns slightly thick/viscous, and fizzes very faintly.
5. BP, W: Fizzes slightly, mostly absorbs.
6. BP, V: Fizzes a bit more, doesn’t absorb as much though.
7. Cornstarch, I: Turns very black-colored, but nothing else; iodine doesn’t really dissolve and just seems to sit on top of the cornstarch.
8. C, W: Water just sits on top; no absorption/dissolving, and no other reactions.
9. C, V: Doesn’t do anything, either.
The interesting thing is that each powder has its own unique set of results with iodine, water, and vinegar; baking soda turned orange. Baking powder turned black in iodine and fizzed to some extent with them all. Cornstarch turned black, and did nothing else with any of them. This also means that someone who didn’t know one of the powders could determine what it was by testing a bit of it with each of the three liquids.
But why? Why can they be so certain one powder is not one of the others? Because each powder is a different chemical/chemical compound, and so each one will undergo chemical reactions with other chemicals that are unique to itself and no other chemical.