Heating Curves & Phase Change Diagrams

States of Matter and KMT Kinetic Molecular Theory: Particles of matter are always in motion explains properties of solids, liquids, gases

Common Characteristics

States of Matter – Know the Phase Changes Fusion Solidification Condensation, Sublimation, Evaporation, Deposition, Fusion (melting), Solidification (freezing)

solid line - equilibrium between phases, both states exist Generic Phase Diagram solid line - equilibrium between phases, both states exist sea level pressure = normal pressure = 1 atm = 101kPa Where is the normal MP? Where is the normal FP?

Review Vocabulary Critical Point: End point of a phase equilibrium curve (liquid/gas line) that designates conditions under which a liquid and its vapor can coexist (their densities are the same, so they are indistinguishable) Normal melting point: Solid  liquids (melts) at 1.0 atm of pressure Normal boiling point: Liquid  gas (boils) at 1.0 atm of pressure Triple point: Solid, liquid, gas phases in equilibrium (all of them exist together at the same time)

Be able to evaluate a Phase Diagram 1 atm = 101kPa Be able to evaluate a Phase Diagram NORMAL = SEA LEVEL a.) At which temperature and pressure do you find the normal freezing point of H2O? b.) At which temperature and pressure do you find the normal boiling point of H2O? c.) At 200 °C and 0.5 atm, water exists as a: solid, liquid, or gas (vapor).

Heating and cooling curves Heating and cooling curves are used to determine how energy influences phase changes during heating and cooling. All phase changes occur at constant temperature. Therefore, average kinetic energy remains constant. During a phase change, the heat added (Potential energy increases) or released (Potential energy decreases) will allow the molecules to move apart or come together.

Energy is given off (product) Energy is added into (reactant)

Kinetic Energy = Temperature (Speed of Molecules) Potential Energy = Spacing between molecules