Can energy be transferred without doing work?(entropy)

  1. From my knowledge, I dont see how it is possible for energy to be transferred without doing work as in the case of entropy. What happens to the unavailable energy? how is it transferred in the first place?
     
  2. jcsd
  3. stewartcs

    stewartcs 2,284
    Science Advisor

    Energy can be transferred by heat or many other forms other than work. Take a look at a Thermodynamics textbook and review the section on the "general energy equation".

    CS
     
  4. In some sense that is kind of a loose definition of heat. Heat is essentially the transfer of energy through any method besides doing work.
     
  5. Mechanical energy can be transferred from kinetic energy T to potential energy V, and back, like in a pendulum. T + V = constant means no energy loss. No "work" is done in this transfer.

    Bob S
     
  6. thanks for answering guys. How come some of the energy transferred is not able to do work? In a chemical reaction where does the unavailable energy come from? I know most energy is transferred as heat. I mean all energy can do work as long as it is transformed right?
     
  7. vanesch

    vanesch 6,236
    Staff Emeritus
    Science Advisor
    Gold Member

    No. That's exactly what entropy means.
     
  8. stewartcs

    stewartcs 2,284
    Science Advisor

    Due to irreversibilities inherent in all systems.

    CS
     
  9. I think I'm almost getting to understand this. How come with an increase in entropy, there is an increase in the magnitude of deltaG, the energy available to do work??? Should'nt it be a decrease as entropy is unavailable energy? Does the value TS (temperature in kelvin multiplied by entropy) in the gibbs free energy formula equal to the value of energy unable to do work??
     
Know someone interested in this topic? Share a link to this question via email, Google+, Twitter, or Facebook

Have something to add?