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How to tell what happens to entropy by seeing a reaction?

Posted: Fri Feb 02, 2018 1:50 pm
by Fenared Ortiz 3K
C12H22O11(s) + O2(g) ---> CO2(g) +H2O(l)

Given this equation how would we be able to tell what happens to entropy?

Re: How to tell what happens to entropy by seeing a reaction?

Posted: Fri Feb 02, 2018 1:56 pm
by Andy Nguyen 1A
Normally, combustion reactions result in an increase in entropy. Based on the phase changes, we see that a solid changed into a gas and liquid, which means an increase in entropy.

Re: How to tell what happens to entropy by seeing a reaction?

Posted: Fri Feb 02, 2018 7:56 pm
by Sue Xu 2K
You can just generally look at the phase of the phase of the reactants and products. In this reaction, the reactants are 1 solid and 1 gas, while the products are 1 liquid and 1 gas. Because liquid has higher entropy than solid, the entropy of the products is higher.

Re: How to tell what happens to entropy by seeing a reaction?

Posted: Sat Feb 03, 2018 11:44 am
by Cynthia Tsang
Like mentioned above, since the entropy of the products is higher, the total entropy would be a positive value.

Re: How to tell what happens to entropy by seeing a reaction?

Posted: Sat Feb 03, 2018 11:56 am
by David Minasyan 1C
Generally speaking, the entropy for gas > liquid > solid.

Re: How to tell what happens to entropy by seeing a reaction?

Posted: Sat Feb 03, 2018 5:54 pm
by Phillip Winters 2F
The phase of the reactants and products are the best way of looking at a reaction and determining how entropy changes, and entropy increases from solid to liquid to gas

Re: How to tell what happens to entropy by seeing a reaction?

Posted: Sat Feb 03, 2018 6:41 pm
by Garret G 2F
This youtube does a really good job of explaining how to predict changes in entropy: https://www.youtube.com/watch?v=ro3AnXdajAM