Question

Magnesium oxidizes via the reaction: 2 Mg + O2 → 2 MgO The reaction has a △Hrxn = -1203 kJ. How much heat (in kJ) is released when you completely react 3.000 moles of O2?

Answer 1

Answer : The amount of heat released is, -3609 KJ

Solution : Given,

Enthalpy of reaction, $\Delta H_{rxn}$ = -1230 KJ

Moles of $O_2$ = 3 moles

The given balanced reaction is,

$Mg+O_2\rightarrow 2MgO$

From the balanced reaction we conclude that

1 mole of $O_2$ releases heat = -1230 KJ

3 moles of $O_2$ releases heat = $\frac{3moles}{1mole}\times -1230KJ=-3609KJ$

Therefore, the amount of heat released is, -3609 KJ