Question

During a voyage to England in 1757, Benjamin Franklin observed, as had sailors for centuries before him, that when cooking grease was thrown from the ship’s galley onto the water, the waves were calmed by the film that formed on the ocean surface. In 1765, Franklin followed up on this observation by placing one teaspoonful (~5 mL) of a fatty acid “oil” on a half-acre pond (roughly 2 × 107 cm2 ), which was just sufficient to form a condensed monomolecular film over the entire surface of the pond. Assume that the fatty acid has a molecular weight of 300 g/mol and a density of 0.90 g/cm3 .

a) How many fatty acid molecules were added to the pond?

b) What is the cross-sectional area of each fatty acid molecule?

c) What is the length of a molecule?

Answer 1