# Physical Behavior of Gases

 Units of Measurement for Gases
 same units as volume:ml,cc,cm3, L
 Temperature Units of Gases
 gases must be measured in Kalvin:C-K= C+ 273F-K= [(F+40)5/9]-40+273
 Absolute Zero
 occurs at 0 K; all molecular motion ceases
 STP(Standard Temperate Pressure) Conditions
 T=0 C and P=1 atm
 Pressure Units
 atmosphere(atm), milimeters of mercury(mmHg/torr), pounds per in2(psi), kilopascals/kilopaskals(Kpa)
 Pressure Unit Conversions
 1 atm=760 mmHg/torr=14.7 psi=101.3 Kpa
 Pressure
 defines as force per unit area : P=F/A
 Atmospheric Pressure
 pressure that is exerted by the gas molecules in Earth’s atmosphere on its surface
 Dalton’s Law of Partial Pressures
 total pressures in any enclosed system is = to the total sum of the partial pressures (Pt=P1+P2+P3…Pn)
 Kinetic Molecular Theory
 explains gas behaviors in terms of molecular motion and distance
 Four Basic Postulates of KMT
 1) gas molecules are spaces far apart; gases are mostly empty space2)gas molecules are in continuous, rapid, and linear motion(average speed of a gas molecule is 1000m/s)3)pressure exerted by gases is a result of collision of gases(these are perfectly elastic) and no energy is lost4) increase in temperature will increase the speed of gas molecules
 Boyle’s Law
 P1*V1=P2*V2(temperature is the constant variable)*pressure is inversely proportional to volume
 Charles’ Law
 V1/T1=V2/T2( pressure is the constant variable)*volume ans temperature are directly proportional
 Gay-Lussac’s Law
 P1/T1=P2/T2(volume is the constant variable)*pressure and temperature are directly porportional
 Combined Gas Law
 P1*V1/T1=P2*V2/T2
 Molecular Volume of Gases
 *at constant temperature and pressure the volume is proportional to the mass * molar volume is = to molar mass/density[(g/mole)/(g/)=L/mole * all gases at the same temperature& pressure have the same molar volume*molecular masses of 2 gases are in the same ratio as their densities (mm1/mm2=d1/d2)
 1 mol of any gas under STP conditions will occupy a vol of 22.4L/mole
 Ideal Gas Law(used when conditions are unchanging)
 *assumes vol is proportional to the # of mols, absolute temp; is inversely proportional to pressure
 PV=nRT(ideal gas aw equation)
 P=pressure(atm), V=volume(L), n=# of mols, T=temperature(K), R= gas constant(0.0821)
 PVM=gRT(alternate for ideal gas law equation)
 *n is substituted by g/M(g=total mass of sample, M=molecular mass)
 Ideal Behavior
 gases behave ideally at high pressure conditions and low temperature conditions
 Law of Combining Volumes
 volume ratio is = to the mole ratio in a balanced chemical equation
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