Question

How many moles are in a 42.5 g sample of magnesium oxide MgO?

Answer 1

To find the molar quantity, you will just simply divide the mass by the molar quantity, to get an answer in moles :

Moles of MgO = 42.5⋅g 40.3⋅g ⋅mol−1=1.05⋅mol

Answer: 1.05•mol