(A) Gold has a density of 19.32 g/cm³. A piece of gold foil is 2.50 cm on each side and 0.100 mm thick. How many atoms of gold are in this piece of gold foil?

(B) If the 1.0 μL sample of liquid ethyl mercaptan from Example 3-2 is allowed to evaporate and distribute itself throughout a chemistry lecture room with dimensions 62 ft x 35 ft x 14 ft, will the odor of the vapor be detectable in the room? The limit of detectability is 9 x 10^-4 μmol/m³.

Example 3-2

The volatile liquid ethyl mercaptan,C₂H₆S, is one of the most odoriferous substances known. It is sometimes added to natural gas to make gas leaks detectable. How many C₂H₆S molecules are contained in a 1.0 μL sample? The density of liquid ethyl mercaptan is 0.84 g/mL.