When it comes to science, a solution doesn’t just mean the correct answer on that chemistry quiz. As a broad term, which at its core refers to a homogeneous mixture of two or more components. Natural solutions are all around us: The air we breathe is a solution, as are many common alloys like steel and bronze. With a little understanding of what makes up a solution, you’ll also be able to easily concoct your own and recognize them when you come across them.
TL;DR (Too Long; Didn't Read)
A solution in science is a homogeneous mixture made up of two or more components, and can be a solid, liquid or gas. Common solutions include steel, air and salt water.
What Makes Up a Solution in Biology
For consideration as a solution, a mixture must have at least two components and be homogeneous. A homogeneous mixture means that the materials involved have dissolved into each other and appear to be one. For instance, when you look at a glass full of soda, you’re looking at water mixed with different ingredients that could include carbon dioxide, sugar and artificial coloring. But you don’t see those ingredients individually, you simply see a glass of carbonated beverage, a homogeneous mixture.
If you look at a bottle of salad dressing made with oil and vinegar, on the other hand, you’re looking at a heterogeneous mixture. Salad dressing is not a solution, because oil and vinegar do not dissolve into each other (even when they briefly appear to if you vigorously shake up the bottle).
Solutions are made up of one major component -- called a solvent -- and at least one other component: A solute. In the glass of soda, the water would be the solvent, and the other minor ingredients like carbon dioxide or sugar would be the solutes.
Sometimes, a liquid solution is made up of only two components, and they are equally represented. In that case, the terms solvent and solute would be interchangeable. Solutions are also common in the other two forms of matter, gases and solids.
Solid solutions form when the solvent, or the major component, is a solid. Gases, liquids and other solids can all be dissolved into the solvent to create a solid solution. Many common solid materials, such as polymers, are examples of solid blends. You’ve probably already encountered some sort of polymer solution today; They’re used to create all kinds of items from plastic water bottles to contact lenses to computers.
Steel is another example of a solid solution, since it is a mixture of iron, carbon and chromium. Other materials used in building, such as bronze and brass, are alloys that are solid solutions. Creating these materials requires detailed scientific knowledge of how to create the equation that allows these ingredients to form together into a homogeneous, solid structure.
When a solution starts with a gas solvent, and then mixes with a gas solute, the result is a gas-gas solution. The most common natural gas solution is the air we breathe every day, which is a mixture of nitrogen, oxygen, carbon dioxide and other gases.