How many molecules of aspirin (formula mass aspirin = 180.0 amu) are there in a 0.250-gram sample?

Question

Quizplus · Accepted Answer

First, we need to calculate the number of moles of aspirin:
moles = mass / molar mass = 0.250 g / 180.0 g/mol = 0.00139 mol
Next, we use Avogadro's number to calculate the number of molecules:
number of molecules = moles x Avogadro's number = 0.00139 mol x 6.02 x 10^23 molecules/mol = 8.36 x 10^20 molecules
Therefore, the answer is B.

How Many Molecules of Aspirin (Formula Mass Aspirin = 180