Predicting chemical reactions

[ScienceNostalgia101]

There are a number of factors in whether or not a particular reaction will occur between chemicals, and/or the extent to which it will. An introductory course in chemistry, even at the university level, goes into Gibbs energy, but never goes so far as to say whether or not it's adequate to predict whether or not any given reaction will occur. (If I had my time back, I'd have asked, but as an undergraduate I was only concerned with getting through it.)

 

Does whether or not a spontaneous reaction will occur depend solely upon the Gibbs energy and activation barrier? Is there software out there that can predict for us the reactions between any combinations of chemicals (ie. so a science teacher doesn't have to try them all to decide which looks the most interesting) or is that prohibited for fear of someone misusing it? And what of non-spontaneous reactions? Is there likewise any "formula" and/or software for predicting the products of electrolysis or no?

[studiot]

47 minutes ago, ScienceNostalgia101 said:

 

Does whether or not a spontaneous reaction will occur depend solely upon the Gibbs energy and activation barrier?

Yes.

But there is another factor in play.

The thermodynamic equations that you are referring to tell us whether a reaction can occur.

can is better than will.

 

This is because the thermodynamic equations do not tell us how fast the reactions go.

There is a thermodynamically derived formula for the rates of both the forward and reverse reaction, but

There is the problem of the mechanism as to how the reactions can occur (reaction apthways) which control the rates.

So it may be possible for the reaction to occur but it rate is negligable, for reaction reasons.

 

Perhaps one of those who still do chemistry every day can suggest one, otherwise I will try to look up some.

The thermodynamic formulae I posted here this morning for someone else.

But, although many reactions do follow these laws all reaction rates should be considered empirical.

 

 

Edited October 20, 2018 by studiot