If the molar mass of a substance is 20.0 g/mol, what is the mass of 4.01 × 10²³ molecules of the substance?

Question

Quizplus · Accepted Answer

First, we need to determine the number of moles in 4.01 × 10^23 molecules. Avogadro's number is 6.022 × 10^23 molecules/mol, so 4.01 × 10^23 molecules is (4.01/6.022) × 10^23/10^23 = 0.666 moles. Then, using the molar mass of 20.0 g/mol, the mass of these moles is 0.666 moles × 20.0 g/mol = 13.32 g, which rounds to 13.3 g.

If the Molar Mass of a Substance Is 20