Learning Objectives
- Describe different types of solutions and give an example of each.
Have you ever been in a band?
Soldiers performing in a band, courtesy of Mass Communication Specialist 2nd Class Michael Hight, U.S. Navy.
Dixieland music arose in New Orleans in the early 1900s. This driving style of music emphasized improvisation on the basic musical theme. Much of the sound quality associated with this music is due to the brass instruments (including the trumpet, trombone, and tuba). New Orleans is still the home of Dixieland, and the French Quarter echoes nightly to the sounds of this exciting music.
Solute-Solvent Combinations
The focus of Water was on water’s role in the formation of aqueous solutions. We examined the primary characteristics of a solution, how water is able to dissolve solid solutes, and we differentiated between a solution, a suspension, and a colloid. There are many examples of solutions that do not involve water at all, or that involve solutes that are not solids. The table below summarizes the possible combinations of solute-solvent states, along with examples of each.
| Solute State | Solvent State | Example |
| liquid | gas | water in air |
| gas | gas | oxygen in nitrogen (gas mixture) |
| solid | liquid | salt in water |
| liquid | liquid | alcohol in water |
| gas | liquid | carbon dioxide in water |
| solid | solid | zinc in copper (brass alloy) |
| liquid | solid | mercury in silver and tin (dental amalgam) |
Gas-Gas Solutions
Our air is a homogeneous mixture of many different gases and therefore qualifies as a solution. Approximately 78% of the atmosphere is nitrogen, making it the solvent for this solution. The next major constituent is oxygen (about 21%), followed by the inert gas argon (0.9%), carbon dioxide (0.03%) and trace amounts of neon, methane, helium, and other gases.
Solid-Solid Solutions
Solid-solid solutions such as brass, bronze, and sterling silver are called alloys. Bronze (composed mainly of copper with added tin) was widely used in making weapons in times past dating back to at least 2400 B.C. This metal alloy was hard and tough, but was eventually replaced by iron.
Liquid-Solid Solutions
Perhaps the most familiar liquid-solid solution is dental amalgam, used to fill teeth when there is a cavity. Approximately 50% of the amalgam material is liquid mercury to which a powdered alloy of silver, tin and copper is added. Mercury is used because it binds well with the solid metal alloy. However, the use of mercury-based dental amalgam has gone under question in recent years because of concerns regarding the toxicity of mercury.
Summary
- Solutions may be composed of a variety of solid, liquid, or gaseous materials.
Practice
Review
- Does a solution have to have water as the solvent?
- Is there an example of a solution where water is the solute?
- When we mix ethylene glycol with the water in our car radiator to prevent freezing, which is the solvent and which is the solute?