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Hey guys, I had a quick chemistry question:
The melting point of is -129 degrees celcius. The melting point of is -190 degrees celcius. Explain why has a higher melting point than .
When i read this question, I was under the impression that C3H8 would have a higher melting point, due to the fact that it has a higher molecular weight than H2, thus increasing the London forces. I would appreciate it if anyone could help me out with this problem.
The mass have nothing to do with the intermolecular bonding, which however is directly associated to melting/boiling points. In non-polar substances (like in your question), the predominating form of intermolecular forces is London forces, and the latter depends on the number of electrons present in each molecule (it's a induced dipole interaction). Therefore, propane (C3H8) has a higher melting point.
Note that the melting point of hydrogen is -259 C and not -129 C and has boiling point -253 C.
Well, Unknown008, increasing mass, generally, means that the number of electrons is increasing (I don't see how we can only add protons and neutrons to a compound). That is essentially what I was saying when I referred to mass. I believe there was a typo in the question, since, from your data the melting point of H2 should be -259 degrees Celsius.
Thanks for pointing that out.