What is the order increasing boiling point for: #"A, butane; B. octane"# #"; C. heptane; D, propane; and E. pentane?"#

Question

Jeremiah Adams · Accepted Answer

#D. A. E. C. B.#

#"Propane",C_3H_8;" Butane", C_4H_10;" Pentane, " C_5H_12; "heptane, "C_7H_16; "Octane, "C_8H_18.#

The following will stick in your memory if you just keep using the formula: methyl, ethyl, propyl, butyl, futile. Of course, the list is in the order of increasing boiling point and molecular mass; the longer and straighter the chain, the more opportunities there are for intermolecular interactions, which leads to a higher boiling point.

You should look up these boilig points! #"n-Pentane"# has a normal boiling point of approx. #36# #""^@C#; #"n-heptane"# boils at #98# #""^@C#. Years ago, during an extended petrol strike, I fuelled my car with laboratory bottles of pentane and hexanes; the car ran rough, but it did run.

In fact, you can model the intermolecular interaction seen in the hydrocarbon boiling points by using bits of string cut to different lengths to illustrate this hydrocarbon volatility. The shorter lengths can be picked out fairly easily, but the longer lengths tend to become entangled and are not as easily separated from each other.

Mateo Aguilar · Answer

undefined The order of increasing boiling point for the given compounds is:

E. pentane < D. propane < A. butane < C. heptane < B. octane