Energetics and Enthalpy
- Created by: Jasmin
- Created on: 10-01-14 11:29
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- Energetics and Enthalpy Change
- Enthalpy Change: ( ) hat energy transferred in a reaction at constant pressure: kJ mol-1
- Standard Conditions: 1 atm pressure, 298K
- (triangle)H = Hproducts - H reactants
- Entahalpy level diagrams shows the relative energy levels of reactants and products
- EXOTHERMIC: negative (trangle)H because products are at a lower energy level than the reactants (products have less energy than reactants)
- Energy has been given out by the system to the surroundings - the surroundings get hotter
- E.g. oxidation
- Diagram
- Energy has been given out by the system to the surroundings - the surroundings get hotter
- ENDOTHERMIC: positive (trangle)H because products are at a higher energy level than the reactants (products have more energy than the reactants)
- Energy has been absorbed by the system from the surroundings - the surroundings get colder
- E.g. melting
- Diagram
- Energy has been absorbed by the system from the surroundings - the surroundings get colder
- The less enthalpy a substance has , the more stable it is
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