Using Hess Law

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  • Created by: Jasmin
  • Created on: 22-01-14 08:47
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  • Using Hess's Law
    • Hess's law states that:
      • The total enthalpy change for a reaction is independent of the route taken, provided the initial and final conditions are the same
    • To be able to draw Hess's law the requirements are that:
      • There are 2 routes between teh reactants and products to be able to draw a Hess cycle
      • The data for the enthalpy changes for one route is given
    • Calculating standard enthalpy changes of formation from standard enthalpy changes of combustion
      • Enthalpy change of formation of a hydrocarbon fuel can be found using enthalpy change of combustion
        • You draw Hess cycle linking the formation of the fuel with the combustion of its constituent elements
          • Example
    • Enthalpy change of formation for any element is 0

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Tryharding

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Where's the example? how come some arrows point to and away from reactants and products in a Hess cycle?

Tryharding

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Where's the example? how come some arrows point to and away from reactants and products in a Hess cycle?

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