States of Matter

Kinetic Theory Kinetic Theory is based on the idea that particles of matter are always in motion. Kinetic Theory is based on the idea that particles of matter are always in motion. Kinetic energy = Energy of motion

Kinetic Theory Gases—particles are far apart with no attraction or repulsion Gases—particles are far apart with no attraction or repulsion Liquids—particles can slide past one another but do experience attraction Liquids—particles can slide past one another but do experience attraction Solids—particles are not free to move but tend to vibrate about fixed points Solids—particles are not free to move but tend to vibrate about fixed points

Kinetic Energy and Temperature Directly Related Directly Related Increase Temperature : Molecules move faster. Increase Temperature : Molecules move faster. Intermolecular forces can’t hold them together. Intermolecular forces can’t hold them together. Decrease Temperature: Molecules move slower. Decrease Temperature: Molecules move slower. Intermolecular forces can now hold them together. Intermolecular forces can now hold them together. Absolute zero (0 K) is the temperature at which the motion of particles theoretically ceases. Absolute zero (0 K) is the temperature at which the motion of particles theoretically ceases.

The K.M.T. of Gases 5 basic assumptions of the kinetic theory as it applies to ideal gases: 5 basic assumptions of the kinetic theory as it applies to ideal gases: Ideal gas: hypothetical gas that fits all assumptions of KMT. Ideal gas: hypothetical gas that fits all assumptions of KMT. 1. Gases consist of large numbers of tiny particles that are far apart. Most of the volume occupied by a gas is empty space. Most of the volume occupied by a gas is empty space.

KMT of gases 2. Collisions between gas particles and between particles and container walls are elastic collisions. An elastic collision: there is no net loss of total kinetic energy. An elastic collision: there is no net loss of total kinetic energy. 3. Gas particles are in continuous, rapid, random motion.

KMT of gases 4. There are no forces of attraction between gas particles. 5. The temperature of a gas depends on the average kinetic energy of the particles of the gas. **The kinetic-molecular theory applies only to ideal gases.**

KMT Key terms Vapor Gas produced from liquid or solid under “normal” conditions VP = Atm. P Gas produced from liquid or solid under “normal” conditions VP = Atm. PFluidity Particles glide easily past one another. Particles glide easily past one another.  liquids and gases flow, both referred to as fluids. Compressibility Particles, which are initially very far apart are crowded closer together. Particles, which are initially very far apart are crowded closer together.

KMT key terms Diffusion spontaneous mixing of the particles of two substances caused by their random motion spontaneous mixing of the particles of two substances caused by their random motionEffusion a process by which gas particles pass through a tiny opening. a process by which gas particles pass through a tiny opening. Real gas gas that does not behave according to the kinetic-molecular theory. gas that does not behave according to the kinetic-molecular theory.Expansion Property of gas that allows it to take shape of container Property of gas that allows it to take shape of container

What is gas pressure? Gas pressure is the force exerted by a gas per unit surface area. Gas pressure is the force exerted by a gas per unit surface area. This pressure results from the collisions of gas particles with objects. This pressure results from the collisions of gas particles with objects. The SI unit of pressure is the pascal (Pa) The SI unit of pressure is the pascal (Pa) 1 atm = 760 mm Hg (or torr) = kPa 1 atm = 760 mm Hg (or torr) = kPa

An Early Barometer The normal pressure due to the atmosphere at sea level can support a column of mercury that is 760 mm high. Barometers are used to measure atmospheric pressure.

Manometer Used to measure pressure produced in lab reactions. Used to measure pressure produced in lab reactions.

Units used in class Be able to use these. You will have to memorize 5 and 6 Be able to use these. You will have to memorize 5 and Newton (force) = kg  m/sec Pressure as pascal = N/m Kilopascal = 1000 pascals Pressure units include: inches Hg, mmHg, torr, atm, kPa Standard= in = 760mm=760 torr = 1atm = 101.kPa STP: standard temperature (0°C, 273°K) and pressure (101.3 kPa) °K = °C + 273

The Nature of Liquids Unlike gas particles, liquid particles are attracted to each other, but they are still able to slide past one another. Unlike gas particles, liquid particles are attracted to each other, but they are still able to slide past one another. More dense than gas More dense than gas Less compressible Less compressible Able to diffuse Able to diffuse

Diffusion of liquids

Liquid key terms Surface tension: a force that tends to pull adjacent parts of a liquid’s to decrease surface area to the smallest possible size. a force that tends to pull adjacent parts of a liquid’s to decrease surface area to the smallest possible size. Capillary action attraction of the surface of a liquid to the surface of a solid attraction of the surface of a liquid to the surface of a solid Usually pulls upward Usually pulls upward

The Nature of Liquids The conversion of a liquid or solid to a gas is called vaporization. The conversion of a liquid or solid to a gas is called vaporization. When this occurs at the surface of a liquid that is not boiling it is called evaporation. When this occurs at the surface of a liquid that is not boiling it is called evaporation. Volatile liquids evaporate at room temp. Volatile liquids evaporate at room temp. A liquid will evaporate faster when heated—more kinetic energy to overcome intermolecular forces. A liquid will evaporate faster when heated—more kinetic energy to overcome intermolecular forces. But…evaporation is a cooling process because particles with the highest energy escape 1 st ! But…evaporation is a cooling process because particles with the highest energy escape 1 st !

The Nature of Liquids The boiling point (bp) is the temperature at which the vapor within the liquid is visible. The boiling point (bp) is the temperature at which the vapor within the liquid is visible. Bubbles form throughout the liquid, rise to the surface, and escape into the air. Bubbles form throughout the liquid, rise to the surface, and escape into the air.

The Nature of Liquids Since the boiling point is where the vapor pressure equals external pressure, the bp changes if the external pressure changes. Since the boiling point is where the vapor pressure equals external pressure, the bp changes if the external pressure changes. Normal boiling point is the bp at normal atmospheric pressure or 1atm. Normal boiling point is the bp at normal atmospheric pressure or 1atm.

The Nature of Solids The particles of a solid are more closely packed than those of a liquid or gas. The particles of a solid are more closely packed than those of a liquid or gas. High density High density Incompressible Incompressible More ordered (organized) More ordered (organized) Little to no diffusion Little to no diffusion

Types of Solid 2 Types Crystalline solid: arranged orderly, geometric, repeating pattern Crystalline solid: arranged orderly, geometric, repeating pattern Examples: salt, metal, diamonds Examples: salt, metal, diamonds Amorphous solid: random arrangement Amorphous solid: random arrangement Examples: glass, plastics, gel Examples: glass, plastics, gel

The Nature of Solids When a solid is heated, the particles vibrate more rapidly as the kinetic energy increases. When a solid is heated, the particles vibrate more rapidly as the kinetic energy increases. Melting point (mp): temperature a solid turns to liquid. Melting point (mp): temperature a solid turns to liquid. Freezing point (fp): same temperature as the mp, but indicates the liquid becoming a solid. Freezing point (fp): same temperature as the mp, but indicates the liquid becoming a solid.

Sodium as a Solid, Liquid, and Gas

Changes in State

CONDENSATION FREEZING DEPOSITION

MELTING VAPORIZATION SUBLIMATION