What is the mass of 18.8 moles of helium (He) atoms?

0.213 g

4.70 g

37.6 g

75.2 g

Which of the following has the greatest mass, in grams?

1 atom of gold (Au)

0.5 mol lead (Pb) atoms

2.0 mole of chlorine (Cl) atoms

25 atoms of mercury (Hg)

3 Answers

  • mass = 18.8 g x 4.00 g/mol=75.2 g

    0.5 mol Pb because mass Pb = 0.5 mol x 207.2 g/mol=103.6 g

  • First:

    18.8 mole He is 18.8 x 4 = 75.2 gram

    For the second question just FORGET about the two distractors that mention atoms.

    So we have the choice between 0.5 mole Pb which is 0.5 x 207 = 103.5 gram

    2.0 mole Cl ATOMS is 2 x 35.5 = 71 gram

    The answer is 0.5 mole Pb

  • A mole is equal to a LOT of atoms (Avogadro’s number); your second question is down to two possibilities. You can find the grams/mole of each element on a periodic table (atomic mass).

    Source(s): scieence

Leave a Comment