Solids, Liquids, and Gases

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Solids, Liquids, and Gases
Chapter 8-Part 1

Matter and Temperature
States of matter Dependent on temperature Solid Liquid Gas Plasma

Solid Definite shape and definite volume
The particles in a solid are held close together by forces between them. The particles are in constant motion but lack the energy to move out of position. Kinetic theory states that all particles are in constant motion Crystalline solids The particles are arranged in repeating geometric patterns. Amorphous solids Solids that have no form – not crystals Glass, some plastics and wax

Liquids Indefinite shape and definite volume
Liquids posses enough kinetic energy to move over and around each other. This allows them to flow But like solids they are held too close together though to be able to compress them. They take the shape of their container

Gases Indefinite shape and indefinite volume
Gases posses enough kinetic energy to separate completely from one another They are free to move in all directions until they have filled their container. P1V1 = P2V2 Since they are not close together the particles of a gas can be squeezed together

Example: the sun and most stars
Plasma-is formed by passing electric currents through gases.  In a plasma with an electrical current running through it, negatively charged particles are rushing toward the positively charged area of the plasma, and positively charged particles are rushing toward the negatively charged area.  In this mad rush, particles are constantly bumping into each other. These collisions excite the gas atoms in the plasma, causing them to release photons of energy. Example: the sun and most stars 99% of the mass of our solar system is plasma <Solid>                <Liquid>                           <Gas>                           <Plasma>

Thermal Expansion In general, when a substance is heated up it takes up more space (expands) and when it cools down it takes up less space (contracts). It takes up more space because the increase in temperature causes and increase in the movement of particles. (ice is an exception)

Changes in State Melting – solid -> liquid
Freezing – liquid -> solid Boiling – liquid -> gas Condensation – gas -> liquid Evaporation – liquid changing to a gas at temperatures below the boiling point. Sublimation – solid -> gas without first melting

Heat and state changes Heat of fusion – energy needed to change a substance from a solid to a liquid. (334kj/kg for water) Heat of vaporization – energy needed to change a substance from a liquid to a gas. (2260 kj/kg for water) In general as a substance is heated it’s temperature increases. This is true except at the exact point of melting and boiling. At this time the energy that is added by heat is used to break the bonds holding the particles together and not to raise the temperature. Why does sweating cool you off?

Density Lab Density = mass/volume
Density is describing how close the atoms are together and how heavy those atoms are. If I were to ask you to place 1 ton of feathers in the parking lot and then place 1 ton of lead in the parking lot, which would make a bigger pile?

Homework Day 1: Read pp. 213-227. Day 2: Vocab. #2,3,7,8,9,10
Day 3: Check. Concepts: #1,2,3, Day 4: Answer questions to Review p. 227 #1,2,3. and Understanding Concepts #14 Day 5: Finish Lab #11-Density, from class. No test this week. You will get the CH. 8 test next week.