Question

If 1g of magnesium and 1g of oxygen reacted, what will be left in the reaction vessel?

a)MgO only
b)MgO and Mg only
c)MgO and O2 only
d) MgO, Mg and O2

Answer 1

The reaction between magnesium (Mg) and oxygen (O2) results in the formation of magnesium oxide (MgO) according to the following equation:

2Mg + O2 → 2MgO

The molar mass of Mg is 24.31 g/mol and the molar mass of O2 is 32.00 g/mol. Therefore, 1 g of Mg is equivalent to 0.041 moles and 1 g of O2 is equivalent to 0.03125 moles.

To determine the limiting reactant, we can calculate the moles of MgO produced from each reactant:

From Mg: 0.041 moles Mg × (2 moles MgO / 2 moles Mg) = 0.041 moles MgO

From O2: 0.03125 moles O2 × (2 moles MgO / 1 mole O2) = 0.0625 moles MgO

Since the amount of MgO produced from Mg is less than the amount produced from O2, Mg is the limiting reactant. Therefore, all the Mg will react to form MgO, leaving no Mg in the reaction vessel. The excess O2 will remain in the reaction vessel since it did not react completely with Mg. Thus, the answer is:

b) MgO only