Final answer:
By determining the moles of magnesium and oxygen that reacted to form magnesium oxide, the stoichiometric ratio of magnesium ions to oxygen ions in the sample has been calculated as 0.9993, very close to the expected 1:1 ratio based on the balanced chemical equation.
Step-by-step explanation:
To calculate the stoichiometric ratio of magnesium ions to oxygen ions in magnesium oxide, we must first determine the mass of oxygen that reacted with magnesium to form magnesium oxide. By subtracting the original mass of magnesium (0.1768 g) from the mass after reaction (0.2932 g), we find that the mass of oxygen that reacted is 0.2932 g - 0.1768 g = 0.1164 g.
The molar mass of magnesium is approximately 24.305 g/mol and that of oxygen is approximately 16.00 g/mol. Thus, the moles of magnesium that reacted are 0.1768 g / 24.305 g/mol = 0.007270 mol and the moles of oxygen are 0.1164 g / 16.00 g/mol = 0.007275 mol.
Since the balanced chemical equation 2Mg + O2 → 2MgO indicates that two moles of magnesium react with one mole of oxygen to form two moles of magnesium oxide, the ideal stoichiometric ratio of Mg to O is 2:1. Considering the experimental molar quantities we calculated, the ratio of magnesium ions to oxygen ions in this sample of magnesium oxide is 0.007270 mol / 0.007275 mol = 0.9993.