Use the following data to calculate the standard heat (enthalpy) of formation, $\Delta$ H°_f , of manganese(IV) oxide, MnO₂(s) .
2MnO₂(s) $\to$ 2MnO(s) + O₂(g) $\Delta$ H = 264 kJ
MnO₂(s) + Mn(s) $\to$ 2MnO(s) $\Delta$ H = -240 kJ

Question

Use the following data to calculate the standard heat (enthalpy) of formation,

\Delta

H°_f , of manganese(IV) oxide, MnO₂(s) .
2MnO₂(s)

\to

2MnO(s) + O₂(g)

\Delta

H = 264 kJ
MnO₂(s) + Mn(s)

\to

2MnO(s)

\Delta

H = -240 kJ

Quizplus · Accepted Answer

The correct answer is A because the standard heat of formation of MnO2(s) can be calculated by adding the enthalpies of the two reactions:2MnO2(s) → 2MnO(s) + O2(g) ΔH°f = 264 kJMnO2(s) + Mn(s) → 2MnO(s) ΔH°f = -240 kJAdding these two reactions gives:3MnO2(s) → 3MnO(s) + O2(g) ΔH°f = 24 kJTherefore, the standard heat of formation of MnO2(s) is -24 kJ/mol.

Use the Following Data to Calculate the Standard Heat (Enthalpy) Δ\DeltaΔ

Use the Following Data to Calculate the Standard Heat (Enthalpy) $\Delta$