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Determining Enthalpy of Vaporization

Posted: Mon Jan 22, 2018 10:11 am
by Anna Goldberg 2I
If you were to have a question that asked you to determine which compound had a higher enthalpy of vaporization, how would you do so?
If, for example, a question asked you to rank H2O, NaCl, and N2 in order of increasing enthalpy of vaporization, how would you determine this?

Re: Determining Enthalpy of Vaporization

Posted: Mon Jan 22, 2018 11:57 am
by Nisarg Shah 1C
I think it depends on the intermolecular forces of each molecule. If they are stronger, then it requires more energy to break those attractions to convert the substance from a liquid to a gas.

Re: Determining Enthalpy of Vaporization

Posted: Mon Jan 22, 2018 12:09 pm
by Anna Goldberg 2I
How are you able to determine the intermolecular forces for these molecules? Does it have to do with covalent/ionic bonding or hydrogen bonding?
As well, do liquids tend to have higher intermolecular forces?

Re: Determining Enthalpy of Vaporization

Posted: Mon Jan 22, 2018 2:40 pm
by Chem_Mod
There are a variety of intermolecular forces that all contribute. However, for that question, you are right. It mainly focuses on ionic versus hydrogen-bonding versus van der Waals forces.

As for the liquids question, they will have stronger interactions than a gas, which is primarily why they are in liquid form.

Re: Determining Enthalpy of Vaporization

Posted: Mon Jan 22, 2018 2:42 pm
by Katelyn 2E
Intermolecular forces are the forces of attraction between molecules. Ranked from weakest to strongest, the IMFs we learned last quarter in Chem 14A are London dispersion forces, dipole-induced dipole, ion-induced dipole, dipole-dipole, hydrogen bonding, and ion-dipole. What you are referring to with covalent and ionic bonds is INTRAmolecular forces.