View Full Version : Easy question about Boiling Point
pop000
Dec 2, 2010, 06:45 AM
Why NeopentaneC(CH3)4 Have Low boiling point then Pentane C5H12? Because the surface area ?
Thanks
DrBob1
Dec 2, 2010, 07:53 AM
Just like the butanes, neopentane has a lower boiling point than it's straight chain isomer n-pentane. And for the same reason. Of course the boiing point of the third isomer, isopentane, is right in the middle. But have you noted their BOILING POINTS? Completely reversed!!
DrBob1
Dec 2, 2010, 07:55 AM
I mean their melting points
pop000
Dec 2, 2010, 08:23 AM
Yes Pentane Melting point – 129.8 °C, Neopentane Melting point −16.6 °C , Butane Melting point −138.4 °C
pop000
Dec 2, 2010, 08:45 AM
Not both Neopentane and Pentane have a straight chain ?
Unknown008
Dec 2, 2010, 10:28 AM
Pentane has a longer straight chain and Neopentane has a shorter one, which is also branched, hence why there is a lower surface area of contact between the latter molecules.
yes Pentane Melting point – 129.8 °C, Neopentane Melting point −16.6 °C , Butane Melting point −138.4 °C
Are you sure those are correct? I thought that pentane is a liquid at room temperature... I guess you mean boiling points.
pop000
Dec 2, 2010, 11:40 AM
Oh OK thanks .
DrBob1
Dec 2, 2010, 04:49 PM
n-Pentane has a MELTING POINT of -129.5 oC, this would seem usual for a typical hydrocarbon, Neopentane melts at -16.6 oC; very high for a hydrocarbon of such a low molecular weight. It thus has a liquid range of about 25 Co.
pop000
Dec 3, 2010, 01:33 AM
Thanks for your answer