Changes of State Chapter 3, Section 2 Page 96

Section 2: Changes of State What happens to a substance during changes between solid and liquid? What happens to a substance during changes between liquid and gas? What happens to a substance during changes between solid and gas?

Changes Between Solid and Liquid The change in state from a solid to a liquid is called melting. The temperature at which a solid melts is its melting point.

Changes Between Solid and Liquid The change from a liquid to a solid is called freezing. The temperature at which a liquid freezes is its freezing point.

Changes Between Liquid and Gas The change from a liquid to a gas is called vaporization.

Water vapor on a lake’s surface. Evaporation Evaporation is when vaporization takes place only on the surface of a liquid. Water vapor on a lake’s surface.

Boiling Boiling is when vaporization takes place below its surface as well as at the surface of a liquid. The temperature at which a liquid begins to boil is its boiling point.

Condensation Condensation is when a gas changes into a liquid. animation Condensation on a bus window

Temperature and Changes of State A beaker of ice at –10ºC was slowly heated to 110ºC. The graph shows how the temperature of the water changed over time. Animation

Temperature and Changes of State Reading Graphs: What two variables are plotted on the graph? Temperature (ºC) on the y-axis, time (minutes) on the x-axis

Temperature and Changes of State Reading Graphs: What is happening to the temperature of the water during segment C of the graph? The temperature is rising from 0ºC to 100ºC.

Temperature and Changes of State Interpreting Data: What does the temperature value for segment B represent? For segment D? Segment B: melting point of ice; segment D: boiling point of water

Temperature and Changes of State Drawing Conclusions: What change of state is occurring during segment B of the graph? During segment D? Change from solid to liquid; change from liquid to gas

Changes Between Solid and Gas There are times when a solid will change directly into a gas. This process is called sublimation. Snow Dry Ice

End of Section: Changes of State