CHEM Help- Express your answer in kilograms using two significant figures.

Question

The density of air at ordinary atmospheric pressure and 25 ∘C is 1.19 g/L What is the mass of the air in a room that measures 14.5×19.5×7.0ft?    

Express your answer in kilograms using two significant figures.

Answer 1

Hello, An,

The challenge here is to convert the volume in metric (liters) when we're given measurements in feet. We could first convert all 3 dimensions into meters (0.3048 meters/foot) and then find the m³, Then use 1979.25 ft³ to covert to liters

But that is too much work for me. I'll use, instead, the conversion factor 28.3168 L/ft³, Now all we need is:

(14.6 ft)*(19.5 ft)*(7.0 ft) = 1979.25 ft³

(1979.25 ft³)*(28.3168 L/ft³) = 56046.03 L

That is multiplied by the density.

(56046.03 L)*(1.19 g/L) = 66694.8 g or 66.6948 kg

67 kg to 2 sig figs