Atmospheric Composition Flashcards
(16 cards)
Define Mixing Ratio
C_x= mols of X / mols of air
or
number density X / Number density Air
unit Mixing Ratio
mol/mol or molmol^-1
ppb or ppm
or
ppbv or ppmv
define mol , n.
mol = n
n= m/M
m= mass of substance
M= Molar Mass or Molecular mass of substance
Define Number Density
n_x = N/V ,
number of molecules per unit of volume
N= number of molecules
V= unit of volume
What is the relationship between number density and mixing ratio
n_x= C_x * n_a
number density of X is equal to mixing ration times number density of air.
C_x = n_x / n_a
units of number density
molecules cm^-3
Find the number density of gas X using the ideal gas law
n_x= (Av * P_x) / RT
what does number density depend on
number density heavily depends on pressure and temperature
unit Mass Concentration, denoted ρ_x
mass of X per unit of air.
g /cm^3
ρ_x =
mass of X / unit volume of air
ρ_x= (n_x*M_x)/Av
Partial pressure, p_x =
p_x= Cx*P
show how to derive partial pressure in terms of number density from the ideal gas law.
p_x = (n_x * RT)/Av
What is the Universal Gas constant, R
8.3145 joules/mol/kelvin or j^-1mol^-1K^-1
What is Avagadro’s Number, Av or N_Av
6.02214 * 10^23 molecules/mol or molecules *mol^-1
units partial pressure
hpa or pa
define partial pressure
measures the frequency of collisions of gas molecules with surfaces: determines the exchange rate of molecules between the gas phase and coexistent condensed phase.
