How many moles of Mg are needed to react with 16g of O2?

Question

2Mg + O2 -- 2MgO

Answer 1

16gO2 x 1mol O2 x 2mol Mg / 32gO2 x 1mol O2 = 1mol

1mol Mg is needed

Answer 2

Molar mass O2 = 32 g/mol
16 g / 32 = 0.5 moles O2
the ratio between Mg and O2 is 2 : 1
2 : 1 = x : 0.5
x = 1 mole Mg needed for the reaction

Answer 3

Since a mole of O2 weighs about 32g, we are starting with one half mole of O2. Since the coefficients of the reactants in the equation indicate that we need two moles of Mg for every one mole of O2, we will need one mole of Mg to completely react with our 16g of O2.

Answer 4

1 mole.