Chemistry Question - Help Needed!?

Question

The denisty of sulfur is 2.07 g/cm^3. How Many S atoms are there in 4.48 cm^3 of sulfur sample?


If S atoms are joined into S8 molecules in the sample, how many S8 molecules are there in the sample?


How do i do this???

Answer 1

4.48cucmS x 2.07gS/1cucmS x 1molS/32gS x 6.02x10^23atomsS/1molS = 1.74 x 10^23 atoms S

1.74x10^23atomsS x 1moleculeS/8atomsS = 2.18 x 10^22 molecules S

Answer 2

Find out how many grams of sulfur are present:
To do this, multiply both numbers, canceling the cm^3 term and leaving the grams. 2.07 * 4.48 = 9.27 grams.

Find out how many moles of sulfur are present:

This requires knowing what the atomic weight of sulfur is. The periodic table lists this as 32.06 grams/mole. Divide the grams of sulfur by the molecular weight to get the number of moles. 9.27 / 32.06 = 0.289 moles. Now find the number of sulfur atoms. This involves knowing what a "mole" is. A mole is just a number, and is about 6.02E23, a number with 23 zeros. Therefore, 0.289 moles is 1.74E23 atoms. If sulfur molecules each have 8 atoms, then the number of molecules is 1.74E23 divided by 8.