1. Kinetic energy is the energy of motion of particles in a substance. Temperature is related to average kinetic energy - higher temperature means higher average kinetic energy. An olympic pool of cool water would have lower kinetic energy than a cup of hot coffee. 2. Liquids and gases are fluids that can flow. In liquids, molecules are close together due to intermolecular forces, but can move past one another. Evaporation occurs when molecules at the surface escape, cooling the liquid. In a closed system, evaporated molecules form a vapor in equilibrium with the liquid. 3. Vapor pressure increases with temperature as molecules gain kinetic energy. The boiling point is reached when vapor pressure equals external pressure and