Mole: The molecular weight of a chemical in grams is equivalent to one mole. Thus, 58.8 grams of NaCl is equivalent to 1 mole of NaCl.
Molar solutions: A 1 M solution contains the molecular weight of the chemical in grams dissolved in a total volume of 1 liter. For example, to prepare a 1 molar solution of NaCl you would dissolve 58.8 grams of NaCl in a final volume of 1 liter.
Percent solutions weight/volume: An N % solution contains N grams of chemical dissolved in a total volume of 100 milliliters of solute.
Percent solutions volume/volume: An N % solution contains N milliliters of liquid chemical dissolved in a total volume of 100 milliters of solute.
Diluting Concentrated Solutions: Use the equation
(Concentration 1) X (Volume 1) = (Concentration 2) X (Volume 2).
So, to prepare 100 ml of a 5M solution from 25M stock, you would set up the equation as follows and solve for (Volume 1).
(25M)(Volume 1) = (5M)(100ml)
(Volume 1) = 20 ml. Thus, take 20 ml of 25M stock and add 80 ml of diluant so that the final volume equals 100 ml.