Sample Problem 6.9
Calculating the Standard Heat of Reaction from Standard Heats of Formation
SOLUTION:
PLAN:
Look up DHof values (Table 6.5) and use Hess’s Law to find DHorxn.
DHorxn = S mDHof (products) - S nDHof (reactants)
DHorxn = [4DHof NO(g) + 6DHof H2O(g)]
- [4DHof NH3(g) + 5DHof O2(g)]
= [(4 mol)(90.3 kJ/mol) + (6 mol)(-241.8 kJ/mol)] -
[(4 mol)(-45.9 kJ/mol) + (5 mol)(0 kJ/mol)]
DHorxn = -906 kJ
| Previous slide | Back to first slide | View graphic version |