Moderators: Chem_Mod, Chem_Admin

Ryan Chang 1C
Posts: 105
Joined: Sat Aug 24, 2019 12:17 am


Postby Ryan Chang 1C » Mon Feb 03, 2020 6:26 pm

(a) Using Trouton’s rule, estimate the boiling point of dimethyl ether, CH3OCH3, given that H(vap) = 21.51 kJ/mol.
(b) Using standard reference sources available in your library or on the Internet, find the actual boiling point of dimethyl ether and compare this value with the value obtained by using Trouton’s rule. Explain any difference.

How would you explain the difference between the estimated boiling point and the actual boiling point?

Posts: 51
Joined: Mon Jun 17, 2019 7:24 am

Re: 4F.15

Postby KeiannaPineda1B » Wed Feb 05, 2020 2:50 am

According to the internet, the experimental boiling point is 248K, which is fair close to the value calculated in part a. The value 85 J/(k*mol) from Truton's rule that entropy of vaporization of organic liquids is solely an average value, and therefore deviate from expected such average value for individual organic liquids.
So in sum, Truton's rule takes into account multiple liquids and when applied to a single organic liquid, this average value is not as precise.

Posts: 50
Joined: Thu Jul 11, 2019 12:16 am
Been upvoted: 1 time

Re: 4F.15

Postby 805303639 » Thu Feb 06, 2020 8:01 pm

Estimate the boiling point from (delta Svap) = (delta Hvap)/T where delta Svap= 85 J K^-1 and delta Hvap = 21.51 kJ/mol. The calculation yields a boiling point of 253 K. The actual boiling point is 248-249 K. Trouton's rule states that roughly the same increase in positional disorder occurs when any liquid vaporizes. When a compound like dimethyl ether does not obey Trouton's rule, its molecules are likely arranged more orderly in the liquid than is typical of most liquids.

Return to “Entropy Changes Due to Changes in Volume and Temperature”

Who is online

Users browsing this forum: No registered users and 1 guest