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I'm going to say B. since H2/Br2 in their standard state is 0.But then you get the occasional question like this and shake your head when you realized you made a careless mistake. Typical MCAT trap questions.
Calculate the deltaH of rxn given that Hf standard for HBr(g) is -36 kJ/mol:
H2(g) + Br2(g) --> 2 HBr (g)
A. -36kJ/mol
B. -72 kJ/mol
C. +72 kJ/mol
D. cannot be determined without more information
The standard state of Br2 is liquid not gas. The correct answer was D since the formation value for Br2(g) was not provided.I'm going to say B. since H2/Br2 in their standard state is 0.
Damn, you got me.The standard state of Br2 is liquid not gas. The correct answer was D since the formation value for Br2(g) was not provided.