Chemistry 30

The standard heats of formation of HCl (g) and HBr (g) are -92.0 kJ/mol and -36.4 kJ/mol respectively. Using this information, calculate ΔH for the following reaction:

Cl_{2 (g)} + 2 HBr _(g) → 2 HCl _(g) + Br_{2 (g)}

Solution:

Solve for ΔH using ΔH_reaction = ΣΔH_products - ΣΔH_reactants

It is helpful to write ΔH_f values directly below the reaction participants, and find the sum of the reaction and product sides of the equation before using that formula: