Answer
15.664 grams of MgO
Work Step by Step
Looking at the thermochemical equation, we see that for an enthalpy change of -1204 kJ, that 2 moles of MgO are produced. Therefore, to find how much MgO is produced for a change of -234kJ we do the following:
-234 kJ * (2 moles/-1204kJ) = 0.3887 moles MgO
Then to find the grams produced we need the molar mass of MgO:
Mg has a mass of 24.3050 g/mol
O has a mass of 15.994 g/mol
MgO has a mass of 40.299 g/mol
Then we have: 0.3887 moles * (40.299 g/ 1 mole) = 15.664 grams
