Qualitative Chemical Analysis
How do scientists know what a sample is when they see a pile of white powder? Is it something common like flour or sugar? Or is it something dangerous? Through the understanding of the chemical makeup of substances and careful testing, scientists can tell the differences between things that look, at least on the surface, the same.
By making observations of how different substances react when mixed with different things, you can learn to identify several white solid powders. Once you have made your observations, have someone set them out randomly and see if you can tell them apart based on your notes. If two are mixed, can you tell what they were?
Observations
You can tell the white powders on the list apart by making a few observations and running a few tests.
- Look at the powder under a magnifying glass. Are there regular crystals? Are there impurities? Are the particles large or small? Jagged or smooth? It there a tint of color? Is there an odor?
- Add room temperature water to some of the sample. Does it dissolve in the water at all? If both the sample and the water are at room temperature, did the temperature change when mixed together? Test the pH with pH paper or a meter. Is it acidic or basic?
- Add iodine. Did it turn a color?
- Add acid. (Yes you can get acid. Pool stores use muriatic acid, HCl, in their pH decreasing products. Please follow safety guidelines when handling this product.) What happened? Did a gas form? Did the color change?
White Powder List
- Sodium Acetate
- White Sand
- Calcium Carbonate
- Vitamin C
- Salt
- Sugar
- Flour
- Cornstarch
- Gelatin
- Alka-Seltzer
- Yeast
- Baking Soda
- Gypsum
Sodium Acetate
Have you ever had salt and vinegar potato chips? Love them or hate them, it’s the sodium acetate, or sometimes sodium diacetate, that gives you that vinegar taste. Sodium acetate is a salt of vinegar, also known as acetic acid.
White Sand
Sand. Yes, it’s a chemical, everything is. Sand is silicon dioxide and can be a white solid. You may already have a lot of experience with sand, but take a moment to really look at it.
Calcium Carbonate
Eggshells, chalk, lime, seashells, antacids, limestone, and pearls. Calcium carbonate is found in many places and has many uses.
Vitamin C
Vitamin C, has the chemical name ascorbic acid. Don’t let that name scare you though. Acids come in all kinds of strengths, and vitamin C is perfectly safe. In fact it is essential.
Salt
Table salt, or sodium chloride, is a white powder. Use kosher salt to make sure you are getting pure salt without additives.
Sugar
Sugar, sucrose to be exact, is a disaccharide composed of a glucose and a fructose.
Flour
White plain flour, the type used for baking, is ground from wheat and has many different chemicals in it. Still, it can easily be identified or ruled out using a few tests.
Cornstarch
Starch is a polymeric chain of glucose, or sugars. It is used in food, cosmetics, laundry additives, and more.
Gelatin
Gelatin is a polymeric chain of protein, often taken from the collagen of animals. It is often used in food, cosmetic products and even in the capsules of some pills.
Alka-Seltzer
Tablets or powders are comprised of baking soda or sodium bicarbonate, aspirin or acetylsalicylic acid, and some vitamin C or ascorbic acid. This combination of ingredients could be confusing when trying to identify it, but some of these materials are distinctive when you know what to look for.
Yeast
When you look at yeast it can be hard to imagine that you are looking at something alive. Yeast is comprised of living eukaryotic cells, and the waste product, a gas, is what bakers use to get dough to rise.
Baking Soda
Baking Soda’s chemical name is sodium bicarbonate. It is used in cooking of course, but it is also used in other industries such as cleaners, agriculture, fire suppressants, and even fireworks (That stinky black snake one).
Gypsum
Gypsum is a mineral with the chemical name of calcium sulfate dihydrate. Many may be familiar with it as plaster of Paris. Gypsum powder, with the water baked off can then be mixed with water where it will set by forming regular gypsum again.