Due: Phase Change Diagram WS Today: Behavior of Gases Variables that affect gases HW Finish POGIL Model 1 Prep Lab Notebook

Standard Temperature and Pressure “STP” Either of these:  273 Kelvin (273 K)  0  C Either of these:  273 Kelvin (273 K)  0  C And any one of these: 1 atm  1 atm  kPa  14.7 lbs/in 2 (psi)  760 mm Hg  760 torr And any one of these: 1 atm  1 atm  kPa  14.7 lbs/in 2 (psi)  760 mm Hg  760 torr

Timeline of Gas Laws and KMT Boyle’s Law Charles’ Law Clausius’ first “complete” version of Kinetic Molecular Theory Bernoulli Hydrodynamica (initial ideas about particle motion)

Kinetic Molecular Theory 1.pertaining to motion. 2. caused by motion. 3. characterized by movement: Running and dancing are kinetic activities. ki ⋅ net ⋅ ic Origin: 1850–55; < Gk kīnētikós moving, equiv. to kīnē- (verbid s. of kīneîn to move) + -tikos Source: Websters Dictionary

Kinetic Molecular Theory  Particles of matter are ALWAYS in motion  Volume of individual particles is  zero.  Collisions of particles with container walls cause the pressure exerted by gas.  Particles exert no forces on each other.  Average kinetic energy is proportional to Kelvin temperature of a gas.

Gas Pressure and its Measurement Pressure = force area Atmosphere Torr Pascal (or kiloPascal)

POGIL – MODEL 1 Work in small Groups Check #4 with Teacher before moving forward See 3 before me Write down “new” information in your notes By the end of Model 1 you should know what the four variables are, the symbol and the unit that affect gases.

Four Variables VariableSymbolUnits TemperatureT°C Kelvin, K (° C+273) PressureP Pascal, Pa Atmosphere, atm Torr mmHG VolumeVLiters, L Amount of Gas (moles) nmoles, mol

Due: POGIL – MODEL 1 Today 1. POGIL Model 2 Have a great Break ! Be ready for lab when you get back!

POGIL – MODEL 2 Work in small Groups Check #4 with Teacher before moving forward See 3 before me Write down “new” information in your notes By the end of Model 1 you should know what the four variables are, the symbol and the unit that affect gases.

Extra Slides

Temperature The temperature of a gas sample is a measurement of the average kinetic energy of the gas molecules in the sample. average kinetic energy The Kelvin temperature scale is used in all gas law calculations. Absolute Zero: The temperature at which all motion stops (0 K). On the Celsius scale, absolute zero is equal to -273ºC.

Kinetic Energy of Gas Particles At the same conditions of temperature, all gases have the same average kinetic energy. m = mass v = velocity small moleculesFASTER  At the same temperature, small molecules move FASTER than large molecules

The Kelvin Scale

Converting Celsius to Kelvin Gas law problems involving temperature require that the temperature be in KELVINS ! Kelvins =  C °C = Kelvins - 273

Standard Molar Volume One mole of a gas at STP has a volume of 22.4 Liters Avogadro’s Hypothesis – Equal volumes of gases at the same temperature and pressure contain equal numbers of particles 1 mol of any gas = x10 23 particles of any gas = 22.4L of any gas

Amount of a Gas Number of moles found in the measured amount of a gas. Need to use density (g/L) since gases are hard to measure by mass