Heat And Entalphy

Jan 13, 2010 at 9:33 PM | Posted by blk A chemists
- Rxns that release heat are exothermic (hot)
- Rxns that absorb heat are endothermic (cold)

Heat is a form of energy
All chemicals have energy stored in them. Stored chemical energy is called enthalpy.
Enthalpy is stored chemical energy.

Enthalpy of gasoline > Enthalpy of water

Exothermic rxns convert enthalpy into heat.
2C8H18 + 25O2 >>> 16CO2 + 18 H2O + Heat
high enthalpy low enthalpy

Enthalpy has a symbol H
Change in enthalpy is Delta H (triangle H)

Exothermic

  • delta H is negative
  • products are lower than reactants
  • heat is released

Endothermic

  • delta H is positive
  • reactants are lower than products
  • heat is absorbed

Delta H and Moles
coefficients can stand for moles or molecules


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1 Responses to Heat And Entalphy

  1. Mr. Doktor Says:
    Posted on January 18, 2010 at 8:09 AM

    Great summary! I think the video is really interesting. However your missing one post on Calorimetry (H=mCT). As well, it might be a good idea to add more examples/solutions.

    All in all good job guys!