Question

Forty miles above Earth's surface the temperature is -23 °C, and the pressure is only 0.20 mm Hg What is the density of air (molar mass - 29.0 g/mol) at this altitude?

Answer 1

Answer:- Density = 4.1*10-4 g/ L

Solution:-

since we know that from ideal gas law

PV = nRT

since we know that

n = mass(m) / molar mass (M)   

and density (d)= mass(m) / Volume (V)

put these values in ideal gas equation

P M = (m/V) RT

then from density

PM = d RT

d = PM / RT .........(1)

since we know that

1 atm = 760 mmHg

P = 0.22 mmHg = 0.0002895 atm

R = 0.08206 L atm / (K mol)

M = 29.0 g/mol

T = -23oC = 250 K

d = (0.0002895 x 29.0) /( 0.08206 x 250)

=4.1*10-4 g/ L

Density = 4.1*10-4 g/ L

Please rate my answer