Exergonic Reactions: Polar Molecule Stability?

[nobahar]

Hello!
Quick question, but it's really bugging me!
Exergonic reactions often yield polar molecules as the products (e.g. combustion of methane). Are these polar molecules 'favourable' because the electrons are spending more time in a lower energy region; or is this wrong, and there's a different reason why polar molecules are more stable?
All responses appreciated.

 

[chemisttree]

Give us an example of the polar molecules you are referring to regarding the combustion of methane. CO2 and H2O? One is polar and one isn't...

 

[nobahar]

Ohhhh, CO₂ isn't polar because the 'pull' of the oxygen atoms is 'balanced'. So I'm guessing polar molecules are not stable more generally? Why would they be, I suppose...
In that case, is there a method of determining the most likely products of a reaction, given that they attempt to form the most stable products?
Thanks for the reply, and any further ones.