Gas Laws Solid -- Liquid -- Gas Gases: low densities easily compressed larger expansion & contraction when T changed THEORY 1. Gases move randomly, no attractive forces, mix quickly together 2. Gases occupy less vol. than the vol. a gas occupies; more vol. between gases than gases themselves 3. K.E. of gas is proportional to K temp.; higher temp results in more K.E. results increase velocity 4. Total K.E. of particles is constant; more forceful collisions results in higher pressure

Pressure: atm: atmospheres mm Hg or torr Temperature: K Volume: L 1 mol of gas = 22.4 L LABELS 1 atm =760 mm Hg 1 mm Hg = 1 torr STP: standard pressure & temp K (0 o C) -- 1 atm (760 mm Hg) P 1 ; V 1 ; T 1 ; n 1 P 2 ; V 2 ; T 2 ; n 2 initial, starting, values final, ending, values

BOYLE’S LAW P V: V inversely proportional to P P 1 V 1 = P 2 V 2 changes in P & constant T V P

CHARLE’S LAW T V : V directly proportional to T V T changes in V & constant P

GAY-LUSSAC T P : P directly proportional to T P T changes in T & constant V

COMBINE GAS LAW changes in T, P, & V nothing held constant

IDEAL GAS LAW PV = nRT n: amt, # of moles of gas R: gas constant Vol: L Temp: K

AVOGADRO’S LAW -- VOL & MOLAR AMTS vol. directly proportional to moles (molar amt) V moles 2 diff. same T & P ( STP )

DALTON’S LAW -- PARTIAL PRESSURE P total = P 1 + P 2 +P 3 + P n sum of all partial pressures contributed from each diff. gas is equal to the Total Pressure Each partial pressure: % gas * P = partial pressure

PROBLEMS BOYLE’S The volume of a balloon is 3.50 L at 1.00 atm. What is the pressure if the balloon is compressed to 2.00 L? P 1 V 1 = P 2 V 2 P 1 = P 2 = V 1 = V 2 = 1 atm X 3.50 L 2.00 L CHARLE’S A balloon has a volume of 43.0 L at 20 o C. What is its volume at -5 o C? V 1 = V 2 = T 1 = T 2 = 43.0 L X

GAY-LUSSAC An aerosol can has an internal pressure of 3.75 atm at 25 o C. What temperature is required to raise the pressure to 16.6 atm? P 1 = P 2 = T 1 = T 2 = 3.75 atm 16.6 atm X COMBINE GAS LAW Scuba divers carry compressed-air tank which hold 8.00 L at a pressure of 140 atm at 20 o C. What is the volume of air in the tank at 0 o C and 1.00 atm? STP conditions P 1 = P 2 = V 1 = V 2 = T 1 = T 2 = 140 atm 1.00 atm 8.00 L X

IDEAL GAS LAW PV = nRT How many moles of gas will occupy a volume of 0.55 L at 347 K and 2.50 atm? P = n = V = T= R = 2.50 atm X 0.55 L 347 K AVOGADRO’S LAW How many moles of methane gas, CH 4, are in a tank that holds 1.00*10 5 L at STP? How many grams of CH 4 ? V 1 = V 2 = n 1 = n 2 = 22.4 L 1*10 5 L 1 mol X 1 mol CH 4 = 16.0 g

DALTON’S PARTIAL PRESSURE P total = P 1 + P 2 + P 3 A closed system contain 3 diff gases (15% CH 4, 45% CO 2, H 2 ). The total pressure is 6.42 atm. What is the partial pressure each gas is contributing? CH 4 =.15 * 6.42 = CO 2 =.45 * 6.42 = H 2 = H 2 = 100% - 15% - 45% = 40%.40 * 6.42 = atm 2.89 atm 2.57 atm Convert total pressure to mm Hg or torr 1 atm = 760 mm Hg

INTERMOLECULAR FORCES Forces that act between diff. molecules Gases: <<< forces, act independently of each other Liquids/Solids: >>>> Forces KEY PTS. Stronger the Force  more difficult to separate atoms/molecules ----  higher melting/boiling pts of subst.

3 MAJOR FORCES Dipole-Dipole London Dispersion Polar Cov. Bonds “net polarity” Weak Force +/- ends of molecules align together Dipole-Dipole London Dispersion Hydrogen Bonding All molecules; behavior due to e - movement w/i subst. Nonpolar molecules form temporary Polarity Weak Force; as mole.wt. Surface Area: > S.A  > Force stronger the molecule held together

Hydrogen Bonding Strong bond Force H bonded to an O, N, or F of one molecule; that H will be attracted to unshared e - pair of O, N, or F of another molecule O H H.. O H H N F Cl.. H H F

LIQUID Energetic molecules of liquid in motion, near surface molecules escape to become vapor (gas?) Closed System: these molecules create vapor pressure according to Dalton’s Law V.P.: depends on Temp & subst. of liquid

SOLIDS Crystalline: ordered arrangement of particles in solid Amphorous: random arrangement IONIC: composed of ions BaCl 2 (s) ---  Ba +2 (s) + 2 Cl -1 (s) MOLECULAR: held together by intermolecular Forces COVALENT NETWORKING: linked by covalent bonds METALLIC: metal ions linked by surrounding “e - field”

CHANGE OF STATE solid – liquid - gas Heat of Fusion: E required to complete the melting of a subst. Heat of Vaporization: E required to complete liquid to vapor (gas) phase PHASE CHANGE ????