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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.
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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.