# Homework Help: Standard entropy of formation ?

1. Jun 1, 2010

### explore88

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. Jun 1, 2010

### graphene

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

3. Jun 1, 2010

### gabriels-horn

Re: standard entropy of formation ??

You should probably write down some reactions to help you visualize the problem.