Units of Measurement for Gases 

same units as volume: ml,cc,cm3, L 

Temperature Units of Gases 

gases must be measured in Kalvin: CK= C+ 273 FK= [(F+40)5/9]40+273 


occurs at 0 K; all molecular motion ceases 

STP(Standard Temperate Pressure) Conditions 



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 


defines as force per unit area : P=F/A 


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) 


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 space 2)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 lost 4) increase in temperature will increase the speed of gas molecules 


P1*V1=P2*V2(temperature is the constant variable) *pressure is inversely proportional to volume 


V1/T1=V2/T2( pressure is the constant variable) *volume ans temperature are directly proportional 


P1/T1=P2/T2(volume is the constant variable) *pressure and temperature are directly porportional 



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) 


gases behave ideally at high pressure conditions and low temperature conditions 


volume ratio is = to the mole ratio in a balanced chemical equation 
