Hess's Law

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Hess's Law
2013-01-15 15:08:47

Advanced Higher Chemistry - Unit Two - Hess's Law
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  1. What does the First Law of Thermodynamics state?
    That energy is conserved
  2. What does Hess's law state?
    The overall reaction enthalpy is the sum of the reaction enthalpies of each step of the reaction
  3. What does the term 'standard enthalpy change' refer to?
    An enthalpy change for a reaction in which the reactants and products are considered to be in thier standard states at a specified temperature
  4. What are standard conditions?
    One atmosphere of pressure and 298K (25°C)
  5. What is the standard enthalpy of combustion?
    The enthalpy change when one mole of a substance is burned completely in oxygen
  6. What is calorimetry?
    The term used to describe the quantitive determination of the change in heat energy which occurs during a chemical reaction
  7. What can be used to measure the heat energy given out or taken in during a chemical reaction?
    A calorimeter
  8. What is the standard enthalpy of formation?
    The enthalpy change when one mole of a substance is prepared from its elements in their standard states
  9. What equation is used to calculate the standard molar enthalpy of formation?
    ΔH˚= ΣΔH˚f (products) - ΣΔH˚f (reactants)