Calculate the number of oxygen atoms in a 80.0 g sample of scheelite (CaWo). Be sure your answer has a unit symbol if necessary, and round it to 3 significant digits.

Explanation:

scheelite is CaWO₄

Mol weight = 288

80 g of scheelite = 80 / 288 = 27.77 x 10⁻² moles

27.77 x 10⁻² moles of scheelite = 27.77 x 10⁻² x 6.02 x 10²³  molecules of scheelite

= 167.17 x 10²¹ molecules of scheelite

1 molecule of scheelite contains 4 atoms of oxygen

167.77 x 10²¹ molecules of scheelite contains 4 x 167.77 x 10²¹ atoms of oxygen .

= 671.08 x 10²¹ atoms of oxygen .

= 671 x 10²¹ atoms .