A A sample of dry air has a temperature of 30C and a specifi

A.) A sample of dry air has a temperature of 30C and a specific volume of 2.0 m³/kg. What is its pressure?

B.) The record low observed surface pressure (in Typhoon Tip, 1979) was 870 hPa; the record high (Mongolia, 2011) was 1087 hPa. Air temperature at the surface can easily vary between -40C and +50C. Find the densities of air corresponding to all four possible combinations of the above extremes.

Solution

Given the sample of dry air has a temperature(T) = 30 ⁰c

specific volume (v)= 2.0 m3/kg

PV = nRT (n= m/M)

Pressure P = nRT/V

R= gas constant = 8.314 J mol^-1 K^-1

molecular mass of dry air M = 26.9645 g.mol^-1

molecular mass of air m = 28.97

n = m/M = 28.97 / 26.9645

= 1.0743

P = nRT/V

= (1.0743 * 8.314* 30) / 2.0

= 133.97 pa