Question

How many sulfur atoms are there in 3.5 mol of sulfur? express your answer using two significant figures?

Answer 1

Sulfur is a chemical element with symbol S and atomic number 16 But no matter what the element or compound is there are always Avogadro number of atoms in one mole So for 3.5 mol Number of atoms = Avogadro number * 3.5 Number of atoms= 3.5 x (6.022 x 10^23) Number of atoms=2.1 x 10^24

Answer 2

Elemental sulfur has a many allotropic modifications.
1) If we use formula S, answer is:
N(S) = n(S) · Na.
N(S) = 3,5 mol · 6·10²³ 1/mol.
N(S) = 2,1·10²⁴ sulfur atoms.
2) If we use formula S₈, answer is:
N(S) = 8 · n(S₈) · Na.
N(S) = 8 · 3,5 mol · 6·10²³ 1/mol.
N(S) = 1,68·10²⁵ sulfur atoms.
Na - Avogadro number.