States of Matter

1. Solid 2. Liquid 3. Gas 4. Plasma

What is volume?  the amount of 3-dimensional space occupied by an object

Characteristics of Solids  Definite shape  Definite volume  Particles packed together tightly  Expands slightly when heated

Characteristics of Liquids  Definite volume  Takes shape of its container  Particles close, but not rigidly packed  Expands when heated

Characteristics of Gases  Indefinite shape – takes shape of its container  Indefinite volume – takes volume of its container  Particles are far apart  Is easily compressed

Gas or Vapor?? Gas Vapor exists in the gaseous state at room temperature. Oxygen, Hydrogen, Nitrogen, Carbon dioxide the gaseous state of a substance that generally exists as a liquid or solid at room temperature. Water vapor, Acetone, Nail polish remover, Perfume

Plasma  exists only at extremely high temperature  an ionized gas  electrons have been stripped away from atoms

Kinetic Theory  All particles of matter are in constant motion:  Particles of a solid vibrate in a fixed location  Particles of liquid can slide past one another. Constantly held close to one another.  Particles of a gas are mostly “free”.

SolidLiquidGas Packing/spacing of particles Movement of particles Can it flow? Take shape of container? Fill volume of container? Compressible? VERY tight packed tight packed VERY far apart Vibrate in place Flow past one another Constantly in motion NO No Yes NO (think about a small amount of liquid vs. a large container) “virtually incompressible” Yes

Phase Changes  a.k.a. changes of state  melting/freezing  vaporization/ condensation  sublimation/ deposition

Thermal Energy & States of Matter  Solid – atoms are in a fixed position, they only vibrate back and forth. Solids have both a definite shape and definite volume.  Liquid – atoms are free to slide over and upon each other. Liquids have a definite volume but not a definite shape.  Gas – atoms are free to move independently of other atoms of the substance. Gases have neither a definite shape or volume.

Phase Changes  Temperature does not change during a phase change

Energy Changes  A process that releases energy is called an exothermic process.  A process that absorbs energy is called an endothermic process.

Phase Changes – see p.85 in text!  TEMPERATURE does not change during a phase change.  ENERGY is being absorbed or released during a phase change.  Red arrows are endothermic!  Blue arrows are exothermic!

Melting Freezing  solid → liquid  particles become more disordered  particles ABSORB energy to increase their disorder  endothermic  liquid → solid  particles become more orderly  particles RELEASE energy to become more ordered  exothermic

Vaporization Condensation  liquid → gas  particles become more disordered  particles ABSORB energy to increase their disorder  boiling, evaporation  endothermic  gas → liquid  particles become more orderly  particles RELEASE energy to become more ordered  exothermic

Sublimation Deposition  solid → gas  NO change to liquid in between!  particles become more disordered  particles ABSORB energy to increase their disorder  dry ice (solid CO 2 ), iodine  endothermic  gas → solid  particles become more orderly  particles RELEASE energy to become more ordered  frost on a window  exothermic

Heating Curve  Graph showing effect on temperature as heat is added to a substance  Shows the physical changes that occur as heat is added (changes in temperature AND changes of state)

These numbers are for water only

Review  Explain the differences between:  melting/freezing  vaporization/ condensation  sublimation/ deposition

Heating Curve Graph Activity

States of Matter – Lesson 3  Gas Laws

Gas Laws!!!  Solid LiquidGas  Orderly not very not at all  Forces strong not very no forces  For phase change in this direction, particles must absorb energy (endothermic reactions)  For phase change in this direction, particles must release energy (exothermic reactions)

Kinetic Theory of Gases  Gas particles are in constant, random motion.  Particles do not interact except when they collide by chance.  No forces of attraction exist between particles.

Gas Pressure  a result of the collisions between gas particles and the walls of the container  measured in pascals (usually kilopascals, kPa)

Pressure  A force distributed over an area.

Gas Pressure  Affected by several factors  Temperature  Volume  Number of Particles P T V Make a card and put your pen Or pencil on the factor that is held Constant. As you move the card Up or down, it will let you know what Happens to each factor!! Example: If Temp is held constant, what Happens to volume when pressure increases? As you hold your pen on the T and move the P up, You will see that V goes down…so, volume decreases!!!!

Pressure and Temperature (at constant volume)  As temperature increases, pressure increases.  As temp increases, kinetic energy of particles increases. Particles collide more often with walls of container and with greater force.

Pressure and Volume (at constant temperature)  As pressure increases, volume decreases. As pressure decreases, volume increases.  As volume increases, pressure decreases. As volume decreases, pressure increases.

Pressure and Volume (at constant temperature) WHY does pressure decrease when volume increases? When the volume of the container increases, there is a larger inside surface of the container. The same number of particles (moving the same as before) will be hitting the inside surface just as often as they did before, except now those hits are over a larger area.

Pressure and Number of Particles (at constant temperature and volume)  Easy!!  More particles = higher pressure  More particles results in more collisions with the walls of the container.

Volume and Temperature (at constant pressure)  As temperature increases, volume increases.  As temp increases, kinetic energy of particles increases. Particles collide more often with walls of container and with greater force. In a flexible container, the walls will expand as a result.

Boyle’s Law the volume of a gas is inversely proportional to its pressure if the temperature and number of particles are constant. P 1 V 1 =P 2 V 2

Boyle’s Law

Charles’s Law – the volume of a gas is directly proportional to its temperature in kelvins if the pressure and the number of particles of the gas are constant.

The Combined Gas Law 

1.6 L 100 kPa P 1 V 1 = P 2 V 2 T 1 T 2

Sasinschools.com  Gas Laws  Quicklaunch #8