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: Standard entropy of formation ?

  1. Jun 1, 2010 #1
    standard entropy of formation ??

    1. The problem statement, all variables and given/known data

    the standard entropy of formation of magnesium is 32.7 J/mol k , That of oxygen gases 205.2 J/mol k

    at that magnesium oxide is 26.9 J/mol k .

    A) What is the entropic energy change when 25 grams of magnesium are burned inexcess oxygen at 25 celsius ??

    B) Does the burning of magnesium in oxygen lead to increase or decrease in entropy in the system ??

    I hope the solution step by step ..

    regards ^_^ ..

    2. Relevant equations



    3. The attempt at a solution
     
  2. jcsd
  3. Jun 1, 2010 #2
    Re: standard entropy of formation ??

    first find the no. of moles of Mg you have.
    that would combine with the same no. of moles of O to give the same no. of moles of MgO.

    entropy change = entropy of form of products - sum of entropy of form of reactants
     
  4. Jun 1, 2010 #3
    Re: standard entropy of formation ??

    You should probably write down some reactions to help you visualize the problem.
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook