1. The document discusses the Avogadro constant of 6.022 x 1023 entities per mole and uses this constant to calculate the number of molecules in different amounts of substances. 2. It also defines molar mass as the mass in grams of one mole of a substance and calculates the molar mass and mass in grams of sodium bicarbonate (NaHCO3). 3. The document provides an example chemical reaction between phosphorus and oxygen and states the mole ratios of reactants and products. It also discusses stoichiometric relationships that quantitatively relate amounts of reactants and products.