[LHM]

What is the most likely boiling point of an equimolar mixture of hexane, C₆H₁₄, and heptane, C₇H₁₆?

Boiling Points:
C₆H₁₄: 69^oC
C₇H₁₆: 98^oC

A) below 69^oC
B) between 69^oC and 98^oC
C) 69^oC
D) 98^oC

I thought that the boiling points would be lowered when they were mixed together, so I chose A, but the answer's B. So can anyone explain why that is?

[Jorriss]

Well, why do you think it would be lower?

[LHM]

Oh nevermind. I just realized that I was thinking about melting point and the van't hoff equation.

But just wondering, from the van't hoff equation for boiling points, why doesn't it raise it to above 98^oC then?

[Jorriss]

Oh nevermind. I just realized that I was thinking about melting point and the van't hoff equation.

But just wondering, from the van't hoff equation for boiling points, why doesn't it raise it to above 98^oC then?

Do you mean boiling point elevation equation? deltaT=mK?

[LHM]

yeah I think so.

[Jorriss]

Think about your boiling point elevation, and then consider that this mixture is equimolar.