Physical Science Chapter 3 Section 3

Changes of State  Fifth change of state is called sublimation  Change of state of a substance is the change of one physical form to another  All changes of state are physical changes In this change, the id of a subs does not change

Energy and Changes of State II  Particles of a subs move diff depending on the state of the sub  Particles have diff amts of energy when the sub is in diff states Particles in liquid have more E than ice Particles in steam have more E than in liquid

Melting: Solid to Liquid  A chng of state that happens when you add E to a sub is melting  Melting is the chng of state from a solid to a liquid Adding E to a solid increases the temp of a solid  The temp at which a sub chgs from a solid to a liquid is the melting pt

More Melting  As temp increases the particles do what?  Melting is an endothermic change because E is gained by the sub as it changes

Freezing: Liquid to Solid  The chg of state from a liquid to a solid is called freezing  Freezing is an exothermic chg because E is removed from the sub as it changes

Evaporation: Liquid to Gas  Evaporation can occur at the SURFACE of a liquid that is below its boiling pt.  Boiling is the change of a liquid to a vapor, or gas, THROUGHOUT the liquid  Boiling occurs when the pressure inside the bubbles, which is called vapor pressure, = the outside pressure on the bubbles, or atmospheric pressure. Temp at which liquid boils is called its boiling pt

More  Atmospheric pressure is lower at higher elevations.  The higher you go above sea level, the fewer air particles there are above you. The boiling pt in Denver is lower than it is in Hillsboro.

Condensation: Gas to Liquid  Condensation is the chg of state from a gas to a L. Condensation & evaporation are the REVERSE of each other.  The Condensation Pt of a sub is the temp at which the gas becomes a L

Sublimation: Solid to Gas  This is the chg of state in which a solid changes DlRECTLY into a gas.  This is an endothermic chg cuz E is gained by the sub as it changes.

Chg of Temp v. Chg of State  When sub lose or gain E, 1 of 2 things happens to the sub: its temp chngs or its state chngs.