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Module 3 Chapter 9 (9.3 Bond Enthalpies (Calculating enthalpy (1) Balanced…

- - - - Enthalpy change of reaction (ΔrH)
        
        Enthalpy change associated with a stated equation in the molar quantities shown in the chemical equation
        
        e.g. 2Mg(s) + O2(g) -> 2MgO(s)
        
        ΔrH= -1204KJmol-1 (as there are 2mole of MgO this is for 2moles)
      - Enthalpy change of formation (ΔfH)
        
        Enthalpy change associated with the formation of 1 mole of a compound from its elements
        
        e.g. Mg(s) +1/2CO2(g) -> MgO(s)
        
        Must be 1mole of compound
        
        ΔfH= -602KJmol-1
      - Enthalpy Change of Combustion (ΔcH)
        
        Enthalpy change associated with the complete combustion of 1mole of a substance
        
        e.g. C4H10(g) + 13/2O2 (g)-> 4CO2(g) + 5H20(l)
        
        ΔcH= -2877KJmol-1
        
        Must be 1mole of compound being combusted
      - Enthalpy Change of Neutralisation (ΔneutH)
        
        Enthalpy change associated with the formation 1 mole of water from a neutralisation reaction between an acid and a base
        
        e.g. HCl(aq) + NaOH(aq)-> NaCl (aq) +H2O (l)
        
        ΔneutH= -57KJmol-1
        
        Actual reaction= H+(aq) + OH-(aq) -> H2O (l)
- - - - 1) Calc. energy transferred
      - 2) ET J->kJ
      - 3)Calc number of moles of fuel burnt
      - 4) q/n= enthalpy change per mole of fuel burnt
      - 5) Exo (-ΔcH) or endo (+ΔcH)
    - - 1) Calc. energy transferred (add volume of both liquids and x1.00 (density of water) to get mass
      - 2) ET J->kJ
      - 3)Calc number of moles of fuel burnt
      - 4) q/n= enthalpy change per mole of fuel burnt
      - 5) Exo (-ΔcH) or endo (+ΔcH)
- - - - Negative ΔH value- Exothermic process
      - Energy is released
    - - Positive ΔH value- Endothermic process
      - Required energy input