A mix of two substances like salt and water, or the air in the atmosphere
A mixture is a PHYSICAL change and can be undone physically.
ALSO, the properties of the components are retained.
The composition can vary if more stuff is just added, whereas a compound can’t just add more stuff.

Heterogeneous Mixture:
Two different substances combined, like salt and water.
The components are big enough to separate them.

Homogeneous Mixtures AKA Solutions:
One or more substances dissolved together into one mixture.
Gaseous mixtures DON’T really count here
The molecules are so well mixed that you can’t see separate components, AKA Uniform

The dominant substance that the solutes mix with

The stuff added that then mixed with the solvent
A solid can ALSO be SOLID, like copper and zinc, or gold and copper to make a wedding ring.

When the solute comes out of the solvent as crystals, like salt in water, when the water evaporates.

Molarity/molar concentration:
Moles of solute divided by the total volume of the solution in Liters.

Stock Solution:
A state in where the solution is just itself, and then you can add water to make it less strong.
C1 and V1

Use this easy equation to find either needed concentration or volume, usually V1.

Example of what Dilution looks like: