Here since magnesium is limiting reagent in the reaction
2Mg+ O2----> 2MgO , 16g of Mg would react with 8 g of O2 to give a max of 16g of MgO.

Understanding the Reaction
When magnesium (Mg) burns in oxygen (O2), it forms magnesium oxide (MgO). The balanced chemical equation for the reaction is:
2 Mg + O2 → 2 MgO
This indicates that 2 moles of magnesium react with 1 mole of oxygen to produce 2 moles of magnesium oxide.
Calculating Moles
- Molar Mass of Magnesium (Mg): 24 g/mol
- Molar Mass of Oxygen (O2): 32 g/mol
- Molar Mass of Magnesium Oxide (MgO): 40 g/mol
To find the number of moles in the given masses:
- Moles of Mg = Mass / Molar Mass = 16 g / 24 g/mol = 0.67 moles
- Moles of O2 = 16 g / 32 g/mol = 0.50 moles
Identifying the Limiting Reactant
The stoichiometry of the reaction shows that 2 moles of Mg require 1 mole of O2.
- From 0.67 moles of Mg, the required O2 = 0.67 / 2 = 0.335 moles
- Available O2 = 0.50 moles
Since 0.335 moles of O2 is less than 0.50, magnesium is the limiting reactant.
Calculating Maximum Amount of Magnesium Oxide
Using the moles of magnesium to find the moles of MgO produced:
- From the reaction, 2 moles of Mg produce 2 moles of MgO. Thus, 0.67 moles of Mg will produce 0.67 moles of MgO.
Now, converting moles of MgO to grams:
- Mass of MgO = Moles × Molar Mass = 0.67 moles × 40 g/mol = 26.8 g
Conclusion
The maximum amount of magnesium oxide formed when 16 g of magnesium is burnt with 16 g of oxygen in a closed vessel is 26.8 g.