We are asked to determine which reactions will have equal ∆H°rxn and ∆H°f
• The enthalpy of formation, ∆H°f is calculated from the formation equation where one mole of product is formed from the standard or elemental forms of each element.
• ∆H°rxn will be equal to ∆H°f if the reaction is a formation equation
For which one of the following reactions is the value of ΔHrxn equal to ΔHf° for the product
A) 2 H2 (g) + O2 (g) → 2 H2O (g)
B) C (s, graphite) + 2 H2 (g) → CH4 (g)
C) Na (s) + Cl (g) → NaCl (s)
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