Question

The value of ΔH for the reaction below is -72 kJ. __________ kJ of heat are released when 1.0 mol of HBr is formed in this reaction. H 2 (g) + Br 2 (g) → 2HBr (g)

Answer 1

Answer:

36 KJ of heat are released when 1.0 mole of HBr is formed.

Explanation:

By Hess law,

The heat of any reaction  ΔH  for a specific reaction is equal to the sum of the heats of reaction for any set of reactions which in sum are equivalent to the overall reaction:

H 2 (g) + Br 2 (g) → 2HBr (g)         ΔH = -72 KJ

This is the energy released when 2 moles of HBr is formed from one mole each of H2 and Br2.

Therefore, Heat released for the formation of 1 mol HBr would be half of this.

Hence,

ΔHreq = -36 kJ

36 KJ of heat are released when 1.0 mole of HBr is formed.