For the species in the reaction below, ΔH°_f is zero for ________. 2Co (s) + H₂ (g) + 8PF₃ (g) → 2HCo(PF₃)₄ (l) A)Co (s) B)H₂ (g) C)PF₃ (g) D)HCo(PF₃)₄ (l) E)both Co(s)and H₂ (g)

Question

Quizplus · Accepted Answer

ΔH°_f is the standard enthalpy of formation, which is the enthalpy change for the formation of one mole of a compound from its constituent elements in their standard states. Since the standard enthalpy of formation for an element in its standard state is defined as zero, ΔH°_f for Co (s) and H₂ (g) is zero. Therefore, the best choice is E as both Co (s) and H₂ (g) have zero ΔH°_f.

For the Species in the Reaction Below, ΔH°f Is Zero

For the Species in the Reaction Below, ΔH°_f Is Zero