Question

the density of air at ordinary atmospheric pressure and 25 degrees celcius is 1.19 g/L. what is the mass, in kilograms, of the air in the room that measures 12.5 times 15.5 times 8 ft?

Answer 1

The mass of the air in the room is 50 kg.

V = lwh = 15.5 ft × 12.5 ft × 8 ft = 1550 ft³

1 ft = 12 in × $\frac{2.54 cm}{1 in}$ = 30.48 cm

V = 1550 ft³ ×$(\frac{30.48 cm}{1 ft})^{3}$ = 4.39 × 10⁷ cm ³ = 4.39 × 10⁷mL = 4.39 × 10⁴ L

Mass = 4.39 × 10⁴ L × $\frac{1.119 g}{1 L}$ = 5.22 × 10⁴ g = 52.2 kg

Note: The answer can have only 1 significant figure, because that is all you gave for the height of the room.

To the correct number of significant figures, the mass of the air in the room is 50 kg.