In class today, we did a mini lab involving three white powders. To the naked eye, there was little to no distinction between the substances, and we could not tell them apart. By adding three different liquids (iodine, water, and vinegar) to the powders, we were able to learn a bit more about their individual chemical and physical properties, in hopes of distinguishing the three. When we added iodine to cornstarch, the cornstarch was slightly absorbed by the iodine and the mix turned black. Our baking soda and iodine combination resulted in the absorption of iodine and the substance turned a yellow-orange color, or the color of iodine. The baking powder and iodine mix fizzed, dissolved, and turned black. Water produced the least reaction, it only fizzed and bubbled when combined with baking powder, but when mixed with cornstarch and baking soda, the concoction simply dissolved. Last but not least, we experimented with vinegar. When combined with cornstarch, the vinegar was simply absorbed. That was not the case with baking soda and baking powder. Both fizzed and dissolved, with the baking soda dissolving quickly and completely, and the baking powder dissolving only somewhat.
Before this lab, I would have been unable to identify one of these powders if it was unknown, but now I understand how to distinguish between them. If I was given one of these powders as an unknown, I could identify it by testing it with different liquids. Now that I know which combinations cause what reactions, and by observing the chemical and physical properties of these reactions, I could tell them apart. Each reaction is different, making these powders relatively easy to identify.