enthalpy - enthalpy describes heat flow in chemical changes...

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enthalpy  - describes heat flow in chemical changes   H = E + PV DH = DE + P DV = q + w - w = q = heat change at constant pressure DH positive w/ endothermic reactions, negative w/ exothermic reactions DH = Hfinal - Hinitial = H(products) - H(reactants) enthalpy of reaction - aka heat of reaction, DHrxn; enthalpy change during reaction extensive property (depends on moles used in reaction) reverse sign of enthalpy if reaction goes in reverse depends on state reactants/products (liquid/solid/gas) o enthalpy of vaporization (DH for liquid to gas conversion) o enthalpy of fusion (DH for solid to liquid conversion) enthalpy of combustion (DH for combusting substance in oxygen) Hess's Law  - DH for reaction equals sum of DH for its parts   same value of DH regardless of how many steps used for the final reaction Calculate DH for 2C(s) + H2(g) >> C2H2(g)   Given: o C2H2 + 5/2 O2 >> 2CO2 + H2O DH = -1299.6 kJ o C + O2 >> CO2
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enthalpy - enthalpy describes heat flow in chemical changes...

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