CATEGORY ： Chemistry 12 Energy 2007/03/03 Sat TB ： CM ： 0 △

Enthalpy



How do we mesure heat?

Joule - it takes 4.19J to head 1.0gram of water １℃

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

Q = mcΔT

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

Q = ? m = 250g c = 4.18J/g℃ ΔT = 85℃-15℃ = 70℃

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

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



ΔH_for → formation
ΔH_c → compustion
ΔH_fus → fusion
ΔH_solid → solidification
ΔH_vap → vaporization
ΔH_sol → solution
ΔH_neu → neutralization
ΔH_dis → dissociation
ΔH_rxn → reaction
ΔH_ion → ionization
ΔH_dec → decomposition
ΔH_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 →　℃　→　37℃ Body Tend
Heat　→ Joule, Calorie



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

Kinetic Energy - Motion
Potential Energy - Position



Coustants: