Class 12 Chemistry

1.1 Expressing concentration Mass percentage, mole fraction, molarity and molality. Only the volume-based measures change with temperature. 1.2 Solubility and Henry's law Solubility of solids depends mainly on temperature. For gases, solubility is proportional to pressure. 1.3 Raoult's law and vapour pressure Each component’s partial vapour pressure is its pure vapour pressure times its mole fraction. 1.4 Ideal and non-ideal solutions Weaker or stronger attraction between unlike molecules raises or lowers the vapour pressure. Azeotropes. 1.5 Colligative properties Four properties that depend only on the number of solute particles, each usable to find a molar mass. 1.6 Abnormal molar mass and the van't Hoff factor Dissociation and association change the number of particles. The van’t Hoff factor i corrects for it.