Solids, Liquids, Gases and Gas Laws

Particles in a liquid are more closely packed causing

attractions between the particles do affect its movement (kind of like a tug of war).

Solid

definite shape and definite volume. Will not change as you move it, but shape and volume can be changed through other forces (pencil, pencil sharpened becomes shorter)

vapor pressure

happens when a liquid is in a container. as it evaporates, it cannot escape and condensates on the container top. (Boiling water in a pot)

pressure

is the result of a force distributed over an area.

Other factors that affect Gas Pressure 1. Temperature 2. Volume 3. Number of particles

1. Temperature - Raising the temp of a gas will increase its pressure if the volume of the gas and them number of particles remains constant (air in tires while driving (friction). 2. Volume - Reducing the volume of gas increases its pressure if the temp of the gas and the number of particles is constant (crushing empty water bottle causes resistance at a point from air remaining in bottle). 3. Number of particles -Increasing the number of particles will increase the pressure of a gas if the temp and volume are constant. (adding more air to a full tire, more collisions, more pressure, eventually container will not hold and it will burst.

Key to behavior of liquids

A liquid takes the shape of its container because particles in a liquid can flow to new locations. The volume of a liquid is constant because forces of attraction keep the particles close together (this force keeps particles from spreading out to fill the container).

phase change (6 phases) 1. Melting/Freezing 2. condensation/vaporization 3. sublimation/deposition

A phase change is the reversible physical change that occurs when a substance changes from one state of matter to another. EX: solid and liquid visible in an iceberg.

The boiling point of a liquid depends on

Atmospheric pressure (can it get loose). Heat releases kinetic energy and movement that shows up in bubbles and determines the boiling point. Boiling is through out a liquid (energy of heat) not at surface of liquid as is evaporation. High atmos cooking, longer because more equal.

Key factor about Gas Pressure

Collisions between particles of gas and the walls of the container cause the pressure in a closed container. The more frequent the collisions, the greater the pressure of the gas.

ENERGY AND PHASE CHANGES

Energy is transferred between substance and its surroundings. ENERGY is either absorbed or released during a phase change.

Boyle's Law 1627

First to describe relationship between pressure and gas. states that the volume of a gas is inversely proportional to its pressure if the temp. and number of particles are constant.

Melting

In Ice, water molecules in fixed positions (seats in theater) till exposed to the energy from environment (air, hot liquid) which causes them to vibrate more quickly and change phase to liquid. At point of 0 celsius, they move from fixed positions. When all molecules have enough energy to move, melting is complete (Liquid). If it is hotter than the melting point, kinetic energy is gained.

Freezing

Liquid, water molecules, loose fixed positions and become slower, giving off energy to the environment and eventuall become rigidly fixed, solid. Does not have to be cold, water to ice, can be cookies baking in an oven. In solid form kinetic energy decreases.

condensation

Phase were gas changes to a solid. Water vapor on mirror after shower, energy transfer from heated, gaseous water to cold of mirror, returns to liquid. (Exothermic - gas gives out energy to environment where it gets stuck (atmospheric pressure, temperature, or a container) and becomes solid again

Key to behavior of Solids

Solids have a definite volume and shape because particles in a solid vibrate around fixed locations (like movie audience in their assigned seats). Vibration is a repetitive back and forth motion. Does not exchange places.

Liquid

material has definite volume but not definite shape (it takes the shape of its container)

Gas

neither the shape or the volume is definite. Ex helium balloon, has shape of balloon, but lighter expanding helium in balloons has more volume than the canister the gas came out of.

EVAPORATION

occurs at the surface of a liquid and is below its boiling point.

vaporization

phase change in which a liquid becomes a gas (endothermic) pulls in the energy from environment to change.

Kinetic Theory of Matter

says that all particles of matter are in constant motion. There are forces of attraction among particles in all matter.

Charles's Law late 1700s

states that the volume of a gas is directly proportional to its temperature in kelvins. if the pressure and the number of particles of gas are constant. V = Volume T= Temp

Kinetic Theory of Gases (3) parts

the constant motion of particles in a gas allows a gas to fill a container of any shape or size. 1. Particles in a gas are in constant, random motion. 2. The motion of one particle is unaffected by the motion of other particles unless the particles collide. 3. Forces of attraction among particles in a gas can be ignored under ordinary conditions.

Kinetic energy

the energy an object has due to its motion. The faster an object moves, the greater its kinetic energy (think baseball)

deposition

the phase in which a gas changes into a liquid WITHOUT first changing into a liquid. (Exothermic - gives energy to environment). EX Frost on window, water vapor gives energy to cold environment and becomes a solid. It loses that much kinetic energy, that quickly to environment.

sublimation

the phase in which a substances changes from a solid to a gas WITHOUT becoming a liquid. EX Dry ice (Carbon dioxide) becomes a gas at concerts at room temperature.