Formation of bonds and heat release

[tonyjk]

Hello,

We know when there's formation of bonds during chemical reaction there's heat release to the surrounding due to conservation of energy. But what I am confused about, is the kinetic energy of the surrounding increase or the kinetic energy of the atoms that made the bonds increase? if it is of the atoms thus the internal energy of the atoms will not change? if it is of the surrounding how the heat is transmitted then?

Thank you

 

[crador]

I'd think it is the bonding atoms that initially gain a kinetic energy boost from bond formation. This makes them hotter than their surroundings. The heat then flows into the surroundings in the standard way - intermolecular collisions and such.

 

[tonyjk]

I'd think it is the bonding atoms that initially gain a kinetic energy boost from bond formation. This makes them hotter than their surroundings. The heat then flows into the surroundings in the standard way - intermolecular collisions and such.

That's what I thought. So at the end the internal energy of the atoms will be less due to the decrease of potential energy and kinetic energy right?

 

[tonyjk]

Does anyone have an answer please?

 

[crador]

On the scale of molecules the kinetic energy of individual motion constitutes heat. The internal energy of a closed system reacting chemically will remain constant. You are exchanging some chemical potential energy for thermal energy.