1) State the chemical reaction
4M + O2 ---> 2M2O
2) State the molar ratios
4 mol M : 1 mol O2 : 2 mol M2O
3) Calculate the number of moles of M2O produced
4 mol M / 2 mol M2O = 2 mol M / x => x = 2 mol M * 2 mol M2O / 4 mol M
=> x = 1 mol M2O
4) Calculate the molar mass of M2O
molar mass = mass in grams / number of moles = 62.0 g / 1 mol = 62.0 g/mol
5) Calculate the atomic mass of M
molar mass of M2O = 2 * atomic mass of M + atomic mass of O =>
62.0 = 2 * atomic mass of M + 16
=> atomic mass of M = [62.0 - 16] / 2 = 23
6) Compare that atomic mass with the atomic masses of the metals in the periodic table.
You will find that 23 is the atomic mass of sodium.
Answer: sodium
