Chapter 13States of Matter

13.1 The Nature of Gases

Kinetic: motion

Kinetic energy: energy in motion

Kinetic Theory: All matter consists of tiny particles that are in constant motion.

3 Kinetic Laws:

1) The particles in a gas are considered to be small, hard spheres with an insignificant volume.

2) The motion of the particles in a gas is rapid, constant and random.

3) All collisions between particles in a gas are perfectly elastic.

Gas Pressure: results from the force exerted by a gas per unit surface area of an object.

● Gas pressure is the result of simultaneous collisions of billions of rapidly moving particles in a gas with an object.

● Vacuum: An empty space with no pressure and no particles.

Atmospheric Pressure: results from the collisions of atoms and molecules in air with objects.

Barometer: Measures the amount of atmospheric pressure. (mmHg)

Pascal (Pa): SI unit of pressure

Standard Atmosphere (atm): pressure required to support 760 mmHg at 25 degree celcius.

1 atm = 760 mmHg = 101.3kPa

● Conversion methods stay the same!!!

● The amount of Kinetic energy varies based on the different substances.

Kelvin Temperature: directly proportional to the average kinetic energy of the particles of the substance.

13.2 - The Nature of Liquids

● The way particles interact within a liquid determine the physical properties of the liquid.

Vaporization: Liquid to gas

Evaporation: When vaporization occurs at the surface of a liquid when it is not boiling.

● During evaporation, only those molecules with a certain minimum kinetic energy can escape from the surface of the liquid.

Vapor Pressure: measure of the force exerted by a gas above a liquid.

● Over time, the number of particles entering the vapor increases and some of the particles condense and return to the liquid.

● When a liquid is heated to a temperature at which particles throughout the liquid have enough kinetic energy to vaporize, the liquid begins to boil.

Boiling Point: The temperature at which the vapor pressure of the liquid is just equal to the external pressure on the liquid.

Altitude and boiling point: Water boils at lower temperatures when placed at higher altitudes.

Example: Water boils at 212 degrees fahrenheit in Sonoma, Ca.

Water boils at 202 degrees fahrenheit in Denver, Co.

Normal Boiling Point: boiling point of a liquid at a pressure of 101.3kPa.

13.3 - The Nature of Solids

● The general properties of solids reflect the orderly arrangement of their particles and the fixed locations of their particles.

Melting Point: is the temperature at which a solid changes into a liquid.

Crystal: particles are arranged in an orderly, repeating, 3-D pattern called a CRYSTAL LATTICE.

Allotropes: 2 or more different forms of the same element in the physical state.

- Carbon, phosphorus, sulfur, oxygen (O2 and O3), Boron, and Antimony.

Amorphous Solid: lacks an ordered internal structure.

- Rubber, plastic and asphalt

Glass: a transparent fusion product of inorganic substances that have cooled to a rigid state without crystallizing.

13.4 - Changes of State

Sublimation: The change of a substance from a solid to a vapor without passing through the liquid state.

● Occurs in solids with vapor pressures that exceed atmospheric pressure at or near room temperature.

Phase Diagrams: Graph representation of the relationship among solid, liquid and vapor states (or phases) of a substance in a sealed container.

● The conditions of pressure and temperature at which two phases exist at equilibrium are indicated on a phase diagram by a line separating the phases.

Triple Point: describes the only set of conditions at which all three phases can exist in equilibrium with one another.

● For water, the triple point is a temperature of .016 degree Celsius and a pressure of .61 kPa (.0060 atm).