Chemistry (Empirical Formula)

Question

Magnesium metal is burned in the presence of atmospheric oxygen to form magnesium oxide.

Mass Mg: 0.1773 g

Mass after reaction: 0.2901 g

Using the given data, calculate the stoichiometric ratio of magnesium ions to oxygen ions in this magnesium oxide sample. Express the ratio as a decimal. Include four significant figures.

What is the empirical formula of magnesium oxide based on this data?

Answer 1

mass of Mg = 0.1773 g

mass of product = 0.2901 g

mass of Oxygen = 0.2901 g - 0.1773 g = 0.1128 g Oxygen

moles Mg = 0.1773 g x 1 mol Mg / 24.31 g = 7.293x10^-3 moles Mg

moles O = 0.1128 g O x 1 mol O / 16 g = 7.05x10^-3 moles O

Ratio Mg : O = 7.293x10^-3 / 7.05x10^-3 = 1.034

Ratio O : Mg = 0.9671

Empirical formula = MgO