1.

Determine the density, specific gravity, and mass of the air in a room whose dimensions are 4m × 5m × 6m at 100 kPa and 25° C.(a) 1.16 kg/m^3, 0.00116, 140 kg(b) 1.17 kg/m^3, 0.00117, 140 kg(c) 1.15 kg/m^3, 0.00115, 140 kg(d) 1.14 kg/m^3, 0.00114, 140 kgThis question was addressed to me in semester exam.My doubt is from Basic Energy Concepts topic in portion Energy Balance of Bioprocess Engineering

Answer»

Correct choice is (b) 1.17 kg/m^3, 0.00117, 140 kg

To ELABORATE: At specified conditions, air can be treated as ideal gas.

The gas constant of air is R = 0.287 K Pa-m^3/Kg K

The density of the air is determined from the ideal-gas RELATION, P = ρ R T to be

ρ = P/RT = (100 kPa)/((0.287 k Pa-m^3/Kg K) (25+273.15)K) = 1.17 kg/ m^3

Then the SPECIFIC gravity of the air becomes

SG = (ρ)/ρH2O = (1.17 kg/m^3)/(1000 kg/m^3) = 0.00117

Finally, the volume and mass of the air in the room are

V = (4m) (5m) (6m) = 120 m^3

m = ρV = (1.17 kg/m^3) (120 m^3) = 140 kg.



Discussion

No Comment Found

Related InterviewSolutions