What amounts do you compare when measuring concentration

Explanation:

The concentration is a measure of how much solute is present in certain amount of solvent or solution. There are many quantitative expressions for the concentration. Some of those expressions are: percentage, molarity, molality, molar fraction, among others.

This table shows the expressions for some concentration measures, showing the amounts compared.

Concentration                         amounts compared in form of ratio

Percentage, mass/mass         (mass of solute / mass of solution) × 100  

Percentage, vol./vol.                (vol. of solue / vol. of solution) × 100

Molarity                                     (moles of solute / liters of solution)

Molality                                      (moles of solute / Kg of solvent)