Daily Science February 18 List two properties of a solid, liquid, and gas Explain why you were able to put more drops of water on the penny than you thought. What is capillary action? Give an example. Give an example of diffusion.

Phase Changes Pg. 91

Phase changes that require energy Melting- particles are speeding up Melting point- point at which solids turn to liquids. Same as freezing point. Vaporization-liquid changes to a gas When it occurs only at the surface-evaporation Vapor exerts pressure over a liquid (vapor pressure) Boiling point- when vapor pressure = atmospheric pressure Sublimation Solid changes directly to a gas

Phase changes that release energy Condensation Gas becomes liquid Happens when particles cool Freezing Liquid to solid Temp at which occurs called freezing point Deposition Gas to solid

Key: Endothermic Exothermic Gas Liquid Solid

Phase diagrams Phase diagram- graph of pressure versus temp T and P have opposite effects Can predict what phase a substance will be in Triple point- represents the temp and pressure where that substance can exist in all three phases Critical point- temperature at which the substance can not exist as a liquid Lines represent points where substance can exist in 2 phases Can determine the melting point and boiling point by determine the temp at the phase change at 1 atm

Critical point

Boiling point and freezing point graphs During a phase change, the temperature does not increase You see a horizontal line during a phase change A positive slope represents a state of matter