Kinetic Theory of Gases SWBAT: Convert units of Celcius to Kelvin SWBAT: Convert units of pressure SWBAT: Identify key components of kinetic theory of gases SWBAT: Use combined and ideal gas law to calculate pressure, temperature. Volume and moles of gases under specific conditions

Kelvin vs. 0 C vs. Fahrenheit Water freezes at 0 0 C or 273 K Water boils at C or 373 K Absolute zero 0K = molecules stop moving

Pressure  Pressure is the force of colliding particles on an object  1atm = 760 mmHg = 101.3KPa  Atm = atmospheres  mmHg = millimeters of mercury  Kpa = Kilopascals

Stoichiometry  Why do we use STP, when finding volume of a gas?  Gases behave differently under different conditions.  Because of this, whenever we compare two gases its often best to use a standard condition, Temperature 0 0 C Pressure101.3KPa or 1 atm

Kinetic Energy  Kinetic Energy of a molecule is the energy which it possesses due to its motion Kinetic Energy  Which state of matter has the greatest kinetic energy? Why do molecules at absolute zero (0K) stop moving?

Liquids  Liquid particles/molecules are in constant motion  An increase in kinetic energy disrupts the attraction the molecules have for one another  Evaporation – molecules with a certain minimum kinetic energy can escape from the surface of the liquid

Solid, Liquid and Gas Molecules  Remember – Molecules in the solid or liquid states are attracted to each other  Example  Water in the liquid phase is made up of water molecules that are attracted to each other through hydrogen bonds Water  If you boil water you break the hydrogen bonds  If you break hydrogen bonds the liquid molecule is now a gas molecule

Gases – Kinetic Theory  Gas particles Gas particles  Are relatively small molecules  Are in constant random motion  Have frequent collisions  Collisions are elastic (transfer energy from one molecule to another)

How to Change the Pressure of a gas Temperature  Which one has greater Pressure? Volume  Which one has greater Pressure?

Combined Gas Law Try the animation  P = Pressure  V = Volume  T = Temperature (in Kelvin)  K= 0 C  The units of P and V do not matter as long as they are the same units. Temp needs to be Kelvin

Ideal Gas Law  R = 8.31 KPa * L / Mol * K  P = Kpa (kilopascals)  V = L (Liters)  T = K (Kelvin, 0 C + 273) Given grams or Molecules? Convert to moles Asked for grams or molecules? Find moles, then convert to grams or molecules

Dalton’s Law of Partial Pressures  The total pressure of a system is equal to the partial pressures of all the different gasses of the system, when volume and temperature are constant