Question About Chemistry that I don't understand

Question

Calculate the mass in grams of 1.60×1024 molecules of propylamine. The chemical formula for propylamine is C3H9N.

Answer 1

C₃H₉N

First, find the molar mass:

3C = 3x12 = 36 g/mol

9H = 9x1 = 9 g/mol

1N = 1x14 = 14

Molar mass = 36 + 9 + 14 = 59 g / mole

Next, using Avogadro's number, figure out how many moles there are in 1.60x10²⁴ molecules:

1.60x10²⁴ molecules x 1 mole / 6.022x10²³ molecules = 2.66 moles

Finally, using the molar mass (above), calculate the mass in grams:

2.66 mols x 59 g / mol = 157 g C₃H₉N