Molecules are changed during chemical reactions. Mixtures consists of two or more substances mixed together but not chemically combined. Substances in mixtures can be separated by physical means. The substances can be present in any amount. The substances in a mixture can be separated by simple physical means.
Solutions are special mixtures formed when one substance dissolves in another.
Solvent - the most abundant substance in the solution. Solute - the least abundant substance in the solution. Solution concentration is a comparison of the amount of solute dissolved in an amount of solvent. One way is to express concentration is by using percentage of mass. Particles are evenly distributed.