Hello /sci/,

As we all know, adding salt to your pot of water will cause the boiling point to rise and the melting point to lower.

Salt dissolves spontanously since a system will always strive to reach a position in which it has as many states as possible. Salt is a crystalline solid thus its component atoms have few states, when dissolved in liquid it will have many orders of magnitude more, making the proces entropically favourable.

Now, my questions are:

1. Does salt dissolve because it is entropically favourable? I am assuming yes, as it is a spontanous process.

2. Does the boiling point of water rise because it would be entropically unfavourable? Once again, I am assuming yes, as boiling results in a rather rapid evaporation, which in turn reduces the number of states that the atoms from salt can occupy. There is less space (liquid) they can take positions in. On the other hand, the whole increase could also simply be caused by electrostatic interactions, as water is polar and the salt dissolved into ions.

3. The same, only for the fusion point. Once again, I am thinking that it does. Freezing would force the salt back into a solid together with the water, a system with the least possible states. As previously, this could still just be simple interactions between the ions and water molecules causing the lowering point.


This question has been bothering me for the past two weeks or so, and I'm afraid that I might be overthinking it. I think I might be giving entropy too much credit. I also might just be rambling (it's been a while since I've last done thermo and I fear that I've forgotten alot of it).