posted
Well, if I am understanding the question, you are trying to integrate with respect to the inverse of dx? I'm not totally convinced that is well defined, but it's been a long day and I haven't had dinner yet. Try using the chain rule to express (1/dx) in terms of just plain dx and some power of x. I'll have another look after dinner, when my brain is operating properly.
Posts: 10645 | Registered: Jul 2004
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posted
If I understand it correctly you are just asking for the integral of 1 and x^2. Those integrals would be x + C and (1/3)x^3 + C.
Posts: 129 | Registered: Sep 2003
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posted
So what was the question supposed to be? For the record, I coulda come up with the other solutions, but I was assuming the question was correct. So there.

posted
Well, it wasn't really homework. That is to say doing that integral was not a necessary part of my homework. It comes from a typo in

d[ΔGfus/T] = - (ΔHfus*dT)/T^2

Which through subsequent steps becomes an expression that relates the mole fraction to depressed freezing point in an ideal binary solid-liquid equilibrium system. This expression has various assumptions in it, for example that the ΔHfus is a constant between ~10 and ~90C, but it gives rather good results for a naphthalene/biphenyl system, ( < 1% error in experimental melting points)

I was attempting to work through the derivation myself, but hit this integral that i couldn't integrate, which it turns out, I didn't have to.