What do you think about this question:
Find Hf of AgI, explain why Hf Br2 is positive
AgI + 1/2Br2=> AgBr +1/2 I2 delta H =a
Hf AgBr =a
Hf Br2 =b
I think this question is poorly set, you should skip it.
Standard enthalpy of formation of any element under standard
conditions is defined as zero.