Hess\' Law Given the following data: calculate DeltaHdegree for the re action: S
ID: 684000 • Letter: H
Question
Hess' Law Given the following data: calculate DeltaHdegree for the re action:Explanation / Answer
Reversed and take 1/3 of the last equation: FeO + 1/3 CO2 -> 1/3Fe3O4 +1/3CO H= 7.67 Take 1/2 of the firstequation: 1/2Fe2O3 + 3/2 CO -> Fe + 3/2CO2 H = 19.5 Reversed and take 1/6 of the second equation: 1/3Fe3O4 + 1/6CO2-> 1/2 Fe2O3 + 1/6 CO H = -3 Write all the reactants on one side and all of the products on oneside : FeO + 1/3 CO2 + 1/2Fe2O3 + 3/2 CO + 1/3Fe3O4 +1/6CO2 -> 1/3Fe3O4 + 1/3CO + Fe + 3/2 CO2 +1/2 Fe2O3 + 1/6CO Cross out any that appears on both sides: leaving you with: Cross out 1/2Fe2O3 that are on both sides Cross out 1/3Fe3O4 that are on both sides For CO: on the left you have: 3/2; on the right you have: (1/3 +1/6 = 1/2); Left over of 1 CO on the left For CO2: left: (1/3+1/6 = 1/2); right : (3/2); Left over of1 CO2 on the right Final equation: FeO + CO -> Fe + CO2 (matches) To get H: add up the individual H H = 7.67 + 19.5 + -3 = 24.2KJ