Question

32 g of a metal, M, reacts with 8 g of oxygen to form an oxide. The formula of the oxide
is MO. What is the atomic mass of M in g mol-1
?

Answer 1

Answer:

Assme 100 g of the compound is present:

39.70 g is O; 60.30 g is M

2) Calculate moles of oxygen:

39.70 g / 16.00 g/mol = 2.48 mol

3) Determine moles of M:

The M to O molar ratio is 1:1

2.48 is to 1 as x is to 1

x = 2.48 mol of M

4) Calculate atomic weight of M and identify it:

60.30 g / 2.48 mol = 24.314 g/mol

M is magnesium