Taking into account the definition of enthalpy of a chemical reaction, the quantity of heat released when 0.75 moles of Mg are burned is 451.5 kJ.
<h3>Enthalpy of a chemical reaction</h3>The enthalpy of a chemical reaction is known as the heat absorbed or released in a chemical reaction when it occurs at constant pressure. That is, the heat of reaction is the energy that is released or absorbed when chemicals are transformed into a chemical reaction.
The enthalpy is an extensive property, that is, it depends on the amount of matter present.
<h3>Heat released in this case</h3>In this case, the balanced reaction is:
2 Mg(s) + O₂ (g) → 2 MgO(s) + 1204 kJ
This equation indicates that when 2 moles of Mg reacts with 1 mole of O₂, 1204 kJ of heat is released.
When 0.75 moles of Mg are burned, then you can apply the following rule of three: if 2 moles of Mg releases 1204 kJ of heat, 0.75 moles of Mg releases how much heat?
<u><em>heat= 451.5 kJ</em></u>
Finally, the quantity of heat released when 0.75 moles of Mg are burned is 451.5 kJ.
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