[vctrm67]

Which equation represents the raction for the standard enthalpy of formation for B5H9 (g) at 298K and 1 atm?
A. 5B(s) + 9H(g) -> B5H9 (g)
B. 2B(s) + 3BH3 (g) -> B5H9 (g)
c. 5/2B2(g) + 9/2H2(g) -> B5H9(g)
D. 5B(s) + 9/2H2(g) -> B5H9(g)

What is the answer and why?

[sjb]

Which equation represents the raction for the standard enthalpy of formation for B₅H₉ (g) at 298K and 1 atm?
A. 5B(s) + 9H(g) B₅H₉ (g)
B. 2B(s) + 3BH₃ (g)  B₅H₉ (g)
c. 5/2B₂(g) + 9/2H₂(g) B₅H₉(g)
D. 5B(s) + 9/2H₂(g) B₅H₉(g)

What is the answer and why?

What is the definition of standard enthalpy of formation