Chapter 8- The Gas Phase Flashcards
Gas pressure units
1atm = 760mmHg = 760 torr = 101.325 kPa
Ideal gas law
PV = nRT
Solving for density
Density = m/V = PM/RT
Number of L that 1mol of a gas at STP takes up
22.4L
Combined gas law
PV/T = PV/T
Calculate a change in volume
V2 = V1 (P1/P2)(T2/T1)
Density
Density = mass/V
Molar mass calculation
M = (density at STP) (22.4)
Avogadros principle
n1/V1 = n2/V2
*as the number of moles of gas increases, the volume increases in direct proportion
Boyles law (must be isothermal)
P1V1 = P2V2
*volume and pressure are inversely related
Charles law (must have constant pressure)
V1/T1 = V2/T2
*volume and temperature are directly related
Gay-lussacs law (constant volume)
P1/T1 = P2/T2
*pressure and volume are directly proportional
Partial pressure calculation
(Moles gas A/total moles of gas) (total pressure)
Vapor pressure
Pressure exerted by evaporated particles above the surface of a liquid
What does increasing partial pressure of a gas do to the solubility?
Increases
Evaporation and condensation equation
Vapor pressure from evaporated molecules forces some of the gas back into the liquid phase until equilibrium is reached b/w evap. and cond.
Average molecular speed of gas particles
KE = (3/2)kBT
kB- 1.38 x 10^-23
T- temperature
Almost impossible to find speed of individual gas molecule. What’s one way to determine an average speed?
Root-mean-square speed (Urms)
squareroot [3RT/M]
*higher temp =faster and larger molecules =slower
Isothermal and isobaric conditions. Equation for rates at which two gases diffuse
r1/r2 = Squareroot [M2/M1]
Diffusion
When gases mix with one another (high to low concentration)
Effusion
When a gas moves the ought a small hole under pressure.
Ideal gas law including density
T = (PM)/ (densityR)
When to use what R-value?
.082 LatmmolK
8.314 JmolK
