Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Help entropy question

  1. May 4, 2008 #1
    An aluminum bar of mass 2.00 kg at 300 degrees C is thrown into a lake. The temperature of the water in the lake is 15.0 degrees C; the specific heat capacity of aluminum is 900 J/(kg* K).

    The bar eventually reaches thermal equilibrium with the lake. What is the entropy change DeltaS_lake of the lake? Assume that the lake is so large that its temperature remains virtually constant.
    Express your answer numerically in joules per kelvin.

    The change in Q of the Lake, heat absorbed by the lake is = 5.13*10^5 J

    When there is a heat transfer of change in Q to a substance at constant temperature T, the entropy change DeltaS of the substance is given by
    \Delta S={\Delta Q}/{T},
    where T is absolute temperature.
     
  2. jcsd
  3. May 4, 2008 #2

    Chi Meson

    User Avatar
    Science Advisor
    Homework Helper

    Where's the problem? You have the Q, you can get the T (temp in Kelvins of the lake) and you have the equation ∆S=Q/T.
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook