Entropy

[Hemichordate]

If you had a reaction where you had, say, 5 moles of gas on the left hand side and 10 moles of gas on the right side + 1 mole solid, would the entropy be + or -?

5Gas <------> 10Gas + Solid

On the one hand, the formation of more gas means greater (+) entropy, but formation of solid means less (-) entropy? So which one is it?

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[RogueUnicorn]

greater entropy in the forward direction. even if it was 5 gas --> 5 gas + 1 solid it's still an increase in entropy.

 

[Omni]

greater entropy in the forward direction. even if it was 5 gas --> 5 gas + 1 solid it's still an increase in entropy.

I'm not sure how correct that is, but you just look at the moles of gas, and ignore everything else, I believe. I've been using that and it hasn't failed me.

 

[pastryman]

yah the forward reaction has greater entropy because youre making more gas and gas is chaotic so youre creating more chaos in the system.

 

[RogueUnicorn]

I'm not sure how correct that is, but you just look at the moles of gas, and ignore everything else, I believe. I've been using that and it hasn't failed me.

there is no such thing as zero entropy. even solids have entropy, and considering the two gasses have comparable energy, adding an additional mole of solid will increase total entropy.

 

[pastryman]

there is no such thing as zero entropy. even solids have entropy, and considering the two gasses have comparable energy, adding an additional mole of solid will increase total entropy.

This is true. He just made products a little more chaotic than reactants which is the definition of increasing entropy.