Chapter 6

Molar Mass and the Mole

• molar mass = formula mass = molecular weight
• sum of the average atomic mass for each atom in chemical formula 

Grams to Moles

• divide by molar mass

Moles to Molecules to Atoms

• N from chemical formula

Percent Composition

• the percent by mass of a particular atom in the chemical formula
• by mass
  • mass A/mass compound
• by molar mass
  • (atoms B x molar mass B)/(molar mass compound)

Empirical, Molecular Formula

• A chemical formula gives the molar ratios of each atom in the molecule
• empirical formula
  • mass to moles 
  • divide by lowest amount of moles
  • convert ratio to lowest whole numbers
• Molecular Formula
  • empirical formula
  • molar mass/empirical formula mass

Molarity, Volume to Moles for solutions

• solutions are the most common form of a mixture
  • defined by the quantity of a pure substance per volume of solution
  • concentration = moles of solute/volume solution

Dilutions

• M1V1 = M2V2