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Moderate

Overall Enthalpy of Formation

APCHEM-IF3EQI

What is the overall change in enthalpy of formation at standard conditions if 2.00 moles of bromine are formed from $NaBr_{(s)}$?

$$ Na_{(s)} + \cfrac{1}{2} Br_{2{(l)}} \rightarrow NaBr_{(s)} \quad \quad \quad \Delta H^\circ = -361.4 \text{ kJ/mol}$$

Process $ \Delta H^\circ $ (kJ/mol)
$ Na_{(s)} \rightarrow Na_{(g)} $ V
$ Na_{(g)} \rightarrow Na^+_{(g)} + e^- \quad $ W
$ Br_{2(l)} \rightarrow 2Br_{(g)}$ X
$ Br_{(g)} + e^- \rightarrow Br^-$ $_{(g)}$ Y
$ Na^+$ $_{(g)} + Br^-$ $_{(g)} \rightarrow NaBr_{(s)} $ Z
A

723 kJ/mol is absorbed.

B

723 kJ/mol is released.

C

1446 kJ/mol is absorbed.

D

1446 kJ/mol is released.