Basic Calculations for Chemical and Biological Analyses. The weight in grams is equal to the numerical value of the atomic weight or molecular weight. The molecular weight of a compound is the sum of the atomic weight of all the atoms that make up one molecule of the compound. This unit is used in place of molecular weight to designate the weight of a compound that does not exist as a discrete molecule. It is the sum of the atomic weights of all elements that comprise the chemical formula of the compound.
Molarity is expressed as moles per liter.
Thus, a 2 molar solution has 2 moles of a substance in a total final volume of 1 liter. Use the periodic table in a chemistry text or the Handbook of Chemistry and Physics to look up the molecular weights of individual atoms in a compound. The molecular weight or formula weight of a chemical is usually printed somewhere on the label or it is possible to calculate the molecular weight from the formula using a periodic table. 1 B. Stock solutions when the diluting agent adds to the final volume. TC pipettes are rare.