CHEM 6A Lecture Notes - Lecture 3: Molar Mass, Molecular Mass, Empirical Formula

• School: UCSD
• Department: Chemistry and Biochemistry
• Course: CHEM 6A
• Professor: Thomas Bussey

Document Summary

Molecular mass is the sum if all the masses of all atoms in a molecule: measured in amu. Formula mass is the sum of the masses of all atoms in a formula unit of an ionic compound: formula unit is the combination of numbers and chemical symbols used to define a molecule, measured in amu. Molar mass is the mass of one mole of atoms, ions, molecules, or formula units: measured in grams. Avogadro"s number: 6. 022 x 10^23, equals 1 mole, makes working with large numbers easier. Percent composition: the percent composition of a compound is a statement of the relative mass each element contributes to the mass of a compound as a whole, calculations: Convert each percent to grams by assuming 100 grams total. Divide each by individual molar mass to find number of moles of each element. Multiply by common multiplier until whole number.