If 58.67g of mercuric oxide were completely decomposed to generate 54.34 g of mercury how many grams of oxygen should have been produced

4.33g

Explanation:

The reaction equation is given as:

        2HgO → 2Hg + O₂

Given parameters:

Mass of HgO = 58.67g

Mass of Hg produced = 54.34g

Unknown:

Mass of oxygen produced = ?

Solution

From the reaction equation, using the mole concept, it is possible to determine the mass of oxygen gas produced.

To do this, we first determine the molar composition of the mass of the given mercury oxide. Then we use the balanced reaction equation to determine the mass of oxygen produced:

Number of moles of HgO =

Molar mass of HgO = 200.6 + 16 = 216.6gmol⁻¹

Number of moles of HgO = = 0.271mol

From the reaction equation, we know that:

           2moles of HgO produced 1 mole of O₂

           0.271moles of HgO would also produce, 0.136mol

Therefore, mass of O₂ gas produced = number of moles of O₂ x molar mass

    Molar mass of O₂ = 16x2 = 32gmol⁻¹

Mass of O₂ gas = 0.136 x 32 = 4.33g

Fe₂O₃  +  3CO  →  2Fe  +  3CO₂

moles of Fe₂O₃  =  mass ÷ molar mass
                          =  100 g ÷  [(56 × 2) + (16 × 2)] g/mol
                          =  100 g ÷ 144 g/mol
                          = 0.694 mol

mole ratio of  Fe₂O₃  :  CO  is   1  :  3
           ∴ if mole of Fe₂O₃ =  0.694 mol
             then mole of CO = 0.694 × 3
                                        = 2.083 mol

mass of CO = mole × molar mass
                    = 2.083 × (12 + 16) g/mol
                    ≈ 58.33 g