On Sapling, they explained that the greater the molar entropy of a liquid, the more ordered it is. However, I thought entropy indicated disorder. How come a larger molar entropy for liquids indicate higher order? Can someone please explain this?
Also, could someone rephrase how to determine which molecule has a higher entropy based on its molecular formula/ structure?
Determining most to least ordered (Sapling #7)
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Re: Determining most to least ordered (Sapling #7)
Regarding that question, the values we have calculated for include the ΔSvap values, or essentially, the change in entropy as a phase change from liquid to gas occurs in the element. The higher the ΔS values, the more disordered the substance will be after changing into its gaseous state compared to its liquid state. As a result, we can assume that the greater the ΔS for the vaporization reaction, the more ordered the liquid form of that substance will be before the vaporization takes place. I believe this is why that particular question says that as the answer. If you have any other questions, or if I haven't explained it properly, feel free to let me know! Hopefully this helps!
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Re: Determining most to least ordered (Sapling #7)
The delta S does not represent the current entropy, but rather the entropy of changing from liquid to gas. If you have a high delta S, that means when you the substances changed it became a lot more disordered. Also, gasses can only get so disordered so if there is a really high delta S, it is probably because the liquid itself was relatively orderly and it had to become A LOT more disordered to become a gas.
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Re: Determining most to least ordered (Sapling #7)
So for this problem deltaS is conditional to just that situation?
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Re: Determining most to least ordered (Sapling #7)
The amount of order or disorder within a liquid molecule also depends on the IMFs of the molecule so CH3OH have hydrogen bonding and have relatively high entropies of vaporization because it is highly ordered in the liquid state and there is much more disorder in its gaseous state hence delta S is positive
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Re: Determining most to least ordered (Sapling #7)
In the problem that you are referring to, they discuss the change in molar entropy due to phase change from liquid to gas. This means that all liquids will have a relatively large change in entropy since they are entering a significantly more disordered phase and we are considering that the gases you are looking at are somewhat similarly disordered, therefore the liquid that has the biggest increase in disorder due to a phase change will have been the most ordered one in the beginning.
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