Question

How many grams of mgo are produced during an enthalpy change of -233 kj ?

Answer 1

Chemical reaction: 2Mg + O₂ → 2MgO. ΔH = -1204 kJ.
ΔH(reaction) = -233 kJ.
From chemical reaction we can se that two moles of magnesium oxide produce -1204 kJ, make proportion:
2 mol : -1204 kJ = n(MgO) : -233 kJ.
n(MgO) = 0,387 mol.
m(MgO) = n(MgO) · M(MgO).
m(MgO) = 0,387 mol · 40,3 g/mol.
m(MgO) = 15,596 g.