Question

Which of the following correctly illustrates the conservation of mass for the reaction below?

4Na(s) + O2(g) → 2Na2O(s)

Answer 1

The balanced equation is :
4 NaO2 = 2 Na2O+3 O2

molar mass NaO2 = 54.99 g/mol

mass NaO2 = 54.99 g/mol x 4 mol= 220 g = mass reactant

molar mass Na2O = 61.98 g/mol

mass Na2O = 61.98 g/mol x 2 mol = 124 g

molar mass O2 = 32 g/mol

mass O2 = 32 g/mol x 3= 96 g

mass products = 124 + 96 = 220 g

mass reactants = mass products