Phase Changes What is Kinetic Theory of Matter? What is involved when matter changes from one state to another?

Day 1: Kinetic Theory of Matter Kinetic theory of matter states: All matter is made of atoms and molecules that act like tiny particles. These tiny particles are always in motion. The higher the temperature of the substance, the faster the particles move, and the more they separate. At the same temperature, more-massive (heavier) particles move slower than less-massive (lighter) particles.

Day 1: Phase Changes Phase change – occurs when a substance changes its state of matter (gas, solid or liquid) During a phase changes the temperature of a substance remains constant and it exchanges energy with it surroundings. Endothermic Reaction – such as melting or vaporization (boiling), the substance absorbs energy Exothermic Reaction – substance releases energy to its surroundings, like in freezing or condensation.

States of Matter

Day 2: Heat Curves Sketch the hurt curve on your paper. Label where the substance is solid, liquid and gas. Label where melting, freezing, vaporization, and condensation are occurring. Does the temperature changing during a phase change? Does the amount of heat added change during a phase change? Why? Heat Curves – are graphs that show the relationship between the change in energy levels to the temperature of the matter. Heat Added

Day 2: Heat Curves Answers For problem 1, compare your answers to the heat curve for water. Freezing occurs at the same place as melting. Condensation occurs at the same place as vaporization. #2 No #3 Yes. It takes more energy to complete a phase change because molecular bonds to be broken or reformed.

Day 3: Practice Questions Which describes the process of the forming of water vapor? At the heat of vaporization point, absorbed thermal energy changes water from a gaseous state to a solid state. At the heat of fusion point, released energy changes water from a gaseous state to a solid state. At the heat of fusion point, released energy changes water from a liquid state to a solid state. At the heat of vaporization point, absorbed energy changes water from a liquid state to a gaseous state. Answer: D

Day 3: Practice Based on the energy changes that occur when materials change state, determine how water freezing on the fruit can protect it from becoming too cold? Answer: The process of freezing is exothermic, so heat is generated as water changes from the liquid to the solid state. This heat protects the tree as the water freezes on it.

Day 3: Final Problem From 20 to 60 oC, what is happening on the graph? The water has used up the added energy. The water molecules have no kinetic energy. The water molecules kinetic energy is increasing The water molecules kinetic energy is decreasing. Energy Answer: C

Day 4: Quiz (Allez!!!)