Comparing Boiling Points of Two Pairs of Materials

[omni]

I have two materials that I have to decide who has a higher boiling point

C2H5OH-CH3OH this is the First duo here i have no idea how to know.

and i have The second pair:CH3CH2CH2CH2OH-CH3OCH2CH2CH3 is will be correct if i will say that CH3CH2CH2CH2OH have the higher boiling point then CH3OCH2CH2CH3 because
he have an a Hydrogen bond?

thanks.

 

[DDTea]

You're right about the hydrogen bonds. Any stabilizing interaction is going to raise the boiling point. Also, consider the molecular mass of the molecules and what effect that has on boiling point. If you make a graph for n-alkanes of boiling point vs. number of carbons, boiling point increases approximately linearly up to a certain point. Another interesting point in regard to longer, n-alkanes is the possibility of molecules "tangling," although you normally won't have to consider that.

 

[omni]

ok and what about the 1st pair?

who have an higher boiling point and why?

thank u.

 

[omni]

and to the C2H5OH-CH3OH someone of them have a hydrogen bonds?

 

[DDTea]

I'm not going to spoonfeed an answer. Reread what I wrote: everything you need to answer this question was explained in my earlier post.

 

[omni]

well ok i know that C2H5OH have more mass then CH3OH.
so the answer if i tell like this: C2H5OH have an higher boiling point then
CH3OH becux it have more mass and Such as high mass of material that it contains more electrons and protons Creating random chance of Dipole is getting higher and we need to use more Energy to over the power between the Molecules, so the boiling point getting higher ?
and i know also the Surface area have Affects on the boiling point.

 

[DDTea]

You're on the right track. In general, increased molecular weight corresponds to higher boiling points. This is due to pretty basic physics, really: a single molecule is converted from the liquid to the gas phase when it has enough translational kinetic energy. Kinetic energy is directly proportional to mass. London dispersion forces aren't particularly important for small atoms like Carbon and Hydrogen though.

On a macroscopic level, boiling occurs when the vapor pressure of the liquid is equal to the atmospheric pressure. Your explanation with surface area is again on the right track, but the devil's in the details: greater surface area doesn't affect the boiling point, per se. At constant atmospheric pressure, the boiling point remains constant. However, molecules closer to the surface will have higher translational kinetic energy and be more likely to escape the liquid phase.

 

[omni]

ok thanks so mush about ur answers it help me.