Calculate the amount of hcn that gives the lethal dose in a small laboratory room measuring 12.0 ft×15.0 ft×8.50ft.

Dimensions of the room in cm = 2.54 x 12 by 15 x 2.54 by 2.54 x 8.5 = 30.48 by 38.1 by 21.59

Volume of the room in cubic cm = 30.48 x 38.1 x 21.59 cubic cm = 25,072.21 cubic cm

Given that the density of air at room temperature is , thus the mass of air in the room = 25,072.21 x 0.00118 = 29.59 g = 0.0296 kg

Given that the lethal dose of HCN is approximately 300 mg HCN per kilogram of air when inhaled, thus the amount of HCN that gives the lethal dose in the small laboratory room is given by 300 x 0.0296 = 8.88 mg.