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Enthalpy



How do we mesure heat?

Joule - it takes 4.19J to head 1.0gram of water ‚PŽ

For water the specific heat capacity is C = 4.19J/gŽ

Q = mcƒ’T

1) how much heat is needed to heat 250 grams of water from 15Ž to 85Ž ?

Q = ? m = 250g c = 4.18J/gŽ ƒ’T = 85Ž-15Ž = 70Ž

Q = (250g)(4,18J/gŽ)(70Ž) = 73150J Q = 73.15 KJ

memo; Q = Joule, m = mass of water (water could be other)



ƒ’H_for ¨ formation
ƒ’H_c ¨ compustion
ƒ’H_fus ¨ fusion
ƒ’H_solid ¨ solidification
ƒ’H_vap ¨ vaporization
ƒ’H_sol ¨ solution
ƒ’H_neu ¨ neutralization
ƒ’H_dis ¨ dissociation
ƒ’H_rxn ¨ reaction
ƒ’H_ion ¨ ionization
ƒ’H_dec ¨ decomposition
ƒ’H_net ¨ net reaction





Energy Substance contains Energy

Energy Rich - CH₄, H₂, C₃H₈, C₂₅H₅₂, CH₃OH

Energy Poor - H₂O, CO₂, NaCl, CaCO₃

(Energy, chemical energy, enthalpy, potential energy, stored energy)
Heat, light - ?


Temperature ¨@Ž@¨@37Ž Body Tend
Heat@¨ Joule, Calorie



Temperture - Average linetic Energy.
Heat - Sum of all energies of all molecules.

Kinetic Energy - Motion
Potential Energy - Position



Coustants:





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