8th Grade Chapter 5 Lesson 4

8 th Grade Chapter 5 Lesson 4 Pgs. 206-218 For Student Use Only

Heat and Phase Change
Three States of Matter:
Solid
Liquid
Gas
Changes due to a loss or gain of heat

Solids to Liquids= melting
This point is called the melting point
Liquid to Solid= freezing
This point is called the freezing point
Freezing point is affected by solutes

Latent Heat
Solid to liquid produces no temperature change
This is called latent heat
Heat of fusion
Heat required to turn a certain amount of solid into a liquid without changing temperature

Evaporation and Condensation
Evaporation- liquid to a gas
Factors that affect evaporation
Higher temperatures
Greater surface area
Air speed over a liquid

Evaporation
Liquids that evaporate quickly are volitile
Liquids that evaporate slowly are involitile

Internal Evaporation
Evaporation that takes place in the liquid as opposed to the usual surface
Requires high heat
This is also called boiling
When evaporation is throughout the liquid
Boiling Point- when boiling takes place

Boiling:
Evaporation will not occur any quicker above 100 degrees
Pressure:
Affects the boiling point
Control the pressure and control the boiling point

Pressure Cooker:
Uses pressure to make food cook faster
Heat of Vaporization:
Heat required to change a given amount of liquid into a gas without raising the temperature

Condensation:
Gas changing into a liquid
This happens when warm things get cold
Saturation Point
When amount of water evaporating equals the amount of condensing

Evaporation and Condensation
Heat flows from higher to lower concentration
Refrigeration is using heat and condensation

Principles of Refrigeration:
When a gas is compressed its temperature rises
When a gas is allowed to expand its temperature falls
When a liquid evaporates it absorbs heat from the surroundings
When a gas condenses is releases heat into its surroundings

Sublimation:
A gas changing directly into a solid
4 th State of Matter:
Plasma- super heated gas

8th Grade Chapter 5 Lesson 4

by MRS.KDUNCAN

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