Order in terms of increasing boiling point?

Question

H_20
NH_3
CH_4

Does anyone know of a helpful online chemistry site, where I can get some really good notes?

Answer 1

CH4 < NH3 < H20
The clue here is the H-bonding strength. The stronger it is, the higher would be its boiling point. In this case, water has the highest boiling point since H-O bond is stronger than H-N or H-C. The weakest H-bonding is H-C; hence, it easily volatize.

Answer 2

The stronger the intermolecular forces in a sample of a molecular substance, the higher the boiling point.

CH4 has the lowest boiling point because it is nonpolar. Only weak London forces attract CH4 molecules to one another.

NH3 has the next lowest boiling point. It is polar (meaning it has dipole-dipole interactions) and it also experiences hydrogen bonding interactions between molecules. These interactions (particularly the hydrogen bonding) are substantially stronger than London forces between CH4 molecules.

H2O has the highest boiling point. Like NH3, it is polar and it also experiences hydrogen bonding interactions. The forces between H2O molecules are stronger than those in NH3 because each H2O molecule is capable of forming 2 hydrogen bonds between water molecules. NH3 is only capable of forming 1.

So the answer is CH4

Answer 3

http://encyclopedia.airliquide.com/encyclopedia.asp?GasID=2