Changes of State Melting Freezing Vaporization Condensation
Change of State A phase change is when a substance converts from one state to another. –Ex. Solid to a liquid All changes of state are ____________changes. During a change of state, the _________of a substance changes. –Particles in liquid water move faster than the particles of ice, therefore liquid water has more energy than ice.
Melting: Solids to Liquids Melting is the change of state from a solid to a liquid. Melting Point is the temperature at which a substance changes from a solid to a liquid. Melting is an endothermic change. –Endothermic Change means that energy is ______________(enters).
Freezing: Liquids to Solids ___________is the change of state from a liquid to a solid. Freezing is an __________ ____________. –Exothermic changes means that energy is ______________(exits).
Vaporization: Liquids to Gases _______________is the change of state from a liquid to a gas. ___________is vaporization that occurs throughout a liquid. A liquid boils at its boiling point. ___________is vaporization that occurs at the ___________of a liquid below its boiling point. Vaporization is _______________.
Condensation: Gases to Liquids _____________is the change of state from a gas to a liquid. Gas becomes a liquid at its condensation point. The _______________of a substance is the same as its boiling point. Condensation is _______________.
Sublimation: Solids Directly to Gas __________________is the change of state from a solid directly to a gas. There is no liquid state. Dry ice is an example of a solid changing straight to a gas. Sublimation is _______________.
Summarizing the Changes of State Change of StateDirectionEndothermic or exothermic Example ____________solid liquidendothermic Freezingliquid solid______________ Liquid water freezes into ice at 0 o C ____________liquid gas______________ Liquid water vaporizes into steam at 100 o C Condensationgas liquidexothermic ____________solid gasendothermic Solid dry ice sublimes into a gas at –78 o C
Heating Curve of Water Time Temperature ( o C) Boiling Point Melting Point Temperature remains at the melting point until all of the solid has melted. Temperature remains at the boiling point until all of the solid has vaporized.