Sciencemadness Discussion Board

From KJ/mole to Celsius

BaFuxa - 13-10-2017 at 04:06

Hi all,

Ok so as I am making my first steps in synthesis I quickly found myself tinkering with bonds and molecules rearrangement.

I can easily get ready-made procedures from the internet but for true experiments I am completely lost.

Say I want to break X-Y bonds within a molecules to get X-Z bonds instead with a one-pot synthesis, how do I know how much heat I have to put in the solution ?

I know the different bonds dissociation energies and how to convert kj/moles to celsius heat units. Now, that may be a very stupid question but how do I go from celsius heat units to regular "temperature"? Is CHU the same as regular degrees Celsius?


j_sum1 - 13-10-2017 at 04:25

I suspect you don't know what you are asking.
Yes, temperature is related to energy -- the average kinetic energy of the molecules in the substance. And yes, energy is stored and released in the breaking and making of bonds. But calculations of bond energy have precisely nothing to do with the temperature required to perform a reaction -- one pot or otherwise.

If you are interested in thermodynamics then get an elementary textbook and start reading -- or go to the Kahn Academy online and lap it up. If you are interested in chemical synthesis then you can do worse than follow established procedures. If you want lo learn more then either research specifics or start at the beginning and build up a knowledge of chemistry. But as it stands, this question is pretty meaningless.

Magpie - 13-10-2017 at 07:48

Quote: Originally posted by BaFuxa  



I know the different bonds dissociation energies and how to convert kj/moles to celsius heat units. Now, that may be a very stupid question but how do I go from celsius heat units to regular "temperature"? Is CHU the same as regular degrees Celsius?



First, forget Amazon as a source of science information. They define the Chu as the amount of heat required to raise the temperature of 1 lb of water 1°C. This, they claim, is equal to 1 BTU. This is wrong the Chu and the BTU are the amount of heat needed to raise the temperature of a lb of water 1°F.

Moles are not a specific substance, but apply to all molecules regardless of composition, molecular wt, etc. If you want to make that conversion it will only apply to water.