Answer:
413.9 grams.
Step-by-step explanation:
First, we need to calculate the molar mass of propylamine (C3H9N):
Molar mass of propylamine = (3 × atomic mass of carbon) + (9 × atomic mass of hydrogen) + atomic mass of nitrogen
Molar mass of propylamine = (3 × 12.01 g/mol) + (9 × 1.01 g/mol) + 14.01 g/mol
Molar mass of propylamine = 59.11 g/mol
Next, we can use Avogadro's number to convert the number of molecules to moles:
1 mole of propylamine = 6.022 × 10^23 molecules
moles of propylamine = (4.21 × 10^24 molecules) / (6.022 × 10^23 molecules/mol)
moles of propylamine = 7.001 mol
Finally, we can use the molar mass to convert moles to grams:
mass of propylamine = moles of propylamine × molar mass of propylamine
mass of propylamine = 7.001 mol × 59.11 g/mol
mass of propylamine = 413.9 g
Therefore, the mass of 4.21×1024 molecules of propylamine is 413.9 grams.