Answer to Question #247518 in Molecular Physics | Thermodynamics for mion

Question

Air in a 10 m^3 tank has a pressure of 500 Kpa and a temperature of 40 degrees Celcius. Determine the mass of air in the tank in kg.

Answer 1

$P = 500\textsf{ kPa}= 500000\textsf{ Pa}\\ V =10\textsf{ m³}\\ T = 40°C = 273 + 40 = 313K\\ \text{ Using, } PV = nRT\\ 500000× 10 = n× 8.314× 313\\ n = 1920\textsf{ moles}$

but the molar mass of air is 28.97 g/mol.

The mass of gas in kg is thus:

1920 x 28.97 = 55622.4 g which is 55.63 kg of air, assumed to be dry.

Remember that this is the absolute mass of air in the tank i.e an amount, when totally removed, leaves nothing behind, only a vacuum$.$