When 2 mol of solid magnesium (Mg) combines with 1 mole of oxygen gas (O2), 2 mol of solid magnesium oxide (MgO) is formed and 1204kJ of heat is released. Write the thermochemical equation for this combustion reaction.
The question asks about the element magnesium reacting with oxygen gas, to form magnesium oxide. The solutions above show magnesium oxide reacting with oxygen gas to form magnesium oxide, which is incorrect.
Mg(s) + 1/2 O2(g) ====> MgO(s) delta H = -602 kJ/mole Mg(s)
2Mg(s) + O2(g) ======> 2MgO(s) delta H = -1204 kJ/mole O2(g)
2MgO + O2 ==> 2MgO delta H = -1204 kJ.
becomes
MgO + 1/2 O2 ==> MgO delta H = -602 kJ/mol for the thermochemical equation.
The thermochemical equation for the combustion reaction of 2 moles of magnesium (Mg) with 1 mole of oxygen gas (O2) to form 2 moles of magnesium oxide (MgO) and release 1204 kJ of heat is as follows:
2Mg(s) + O2(g) -> 2MgO(s) + 1204 kJ
Note: The "->" arrow signifies the direction of the reaction, with the reactants on the left side and the products on the right side.
To write the thermochemical equation for the combustion reaction between magnesium and oxygen, we need to include the chemical formulas and the energy change.
The balanced equation for the reaction is:
2Mg + O2 -> 2MgO
This equation shows that 2 moles of solid magnesium react with 1 mole of oxygen gas to produce 2 moles of solid magnesium oxide.
The energy change, which is -1204 kJ (negative because it is a heat release), is typically written above the reaction arrow. Therefore, the complete thermochemical equation is:
2Mg + O2 -> 2MgO ΔH = -1204 kJ
This equation indicates that for every 2 moles of magnesium reacting with 1 mole of oxygen, 1204 kJ of heat is released.