- #1
Jilly
- 12
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Homework Statement
At an altitude of 50 km, the average atmospheric temperature is 0C. what is the average number of air molecules per cm^3 of air at this atmosphere?
Given formula:
P(sub h) =
P(sub 0) x e^(-Mgh/RT) =
-(Mgh x 10^5)/2.303RT
Assuming P = 1 atm at sea level and h in km
M=28.97g/mol=28.97cm^3/mol
g = 9.81 m/s^2 = .0981 km/s^2
h = 50 km
R = 8.314 J/K•mol =
82.06cm^3•atm/K•mol
T = 0 C = 273.15 K
I'm having trouble because using the scale height form of the equation (second form) I get lost in the units, and I'm receiving an error on my TI using the first.
The Attempt at a Solution
Using second equation:[/B]
Log P(sub h) =
(-Mgh x 10^5)/2.303RT =
-(28.97)(.0981)(50)(10^5)/
(2.303)(82.057)(273.15) =
-275.28
10^(-275.28) = 5.23... But the units after the conversion don't add up ... Suggestions?