How many moles of steric acid are contained in 0.25 ml of a hexane solution containing 5.4 x 10^-4 g stearic acid/l?

First, we determine the mass of stearic acid in the solution by multiplying the given concentration by the volume.

mass of stearic acid = (5.4 x 10^-4 g/L) (0.25 mL) (1000 mL/1L)

= 0.135 g

Then, we divide this amount by the molar mass in order to obtain the number of moles of stearic acid. The molar mass of stearic acid is 284.4772 g/mol.

moles stearic acid = 0.135 g / (284.4772 g/mol)

= 4.75 x 10^-4 mol