Phases of Matter

Phases Review Solid Liquid Gas Plasma Definite shape & volume Definite volume but can change shape (depends on container) Gas No definite shape or volume Plasma Ionized gas

As an object changes phase, the number of atoms does not change just their arrangement.

Temperature Temperature is the amount of kinetic energy (KE) an object has The greater the temperature, the more KE, the more the atoms move All molecules move if their temperature is above 0 K (absolute zero)

Objects at the same temperature have the same KE even though objects have different properties they have same KE at the same temperature.

If all molecules have the same kinetic energy at the same temperature, why don’t all things have the same melting and boiling points? Different molecules have different intermolecular forces acting on them Stronger the intermolecular force, the higher the melting and boiling points

The more KE an object has, the faster the molecules will move (creating disorder). Entropy = disorder As temperature increases, entropy increases. Amount of entropy Solid < liquid < gas < plasma

Kinetic Theory of Gases Gas molecules are in constant, rapid, straight line motion (have high temperatures, therefore high amounts of KE)

Kinetic Theory of Liquids When the temperature decreases, kinetic energy decreases. Molecules move slower. Molecules slow down enough that molecules are attracted to each other enough to overcome having random, straight line motion causes molecules to become liquids (molecules can still slide past each other.)

Kinetic Theory of Solids As molecules in a liquid cool, they move more slowly. Eventually, temperature is reached at which molecules take a fixed position in a regular geometric pattern Molecules are held at fixed positions by strong intermolecular forces

Melting As temperature increase, molecules vibrate faster and farther apart until the strong intermolecular forces are overcome enough for the molecules to glide past each other Melting = endothermic.

Changes of Phase terms Freezing: liquid  solid Melting: solid  liquid Condensation: gas  liquid Evaporation: liquid  gas Sublimation: solid  gas Deposition: gas solid

Phase Change Diagram

Solutions Solutes impact boiling and melting points Boiling point is raised when solutes are present Presence of solutes makes it difficult for water to become a gas Freezing point is depressed (lowered) When solute is present in solvent, harder for solvent molecules to make crystal like structure Do as two labs instead of giving them the answer…have this be an inquiry activity!!!!