[zahc]

Hi all,something has me confused.I read that when bonds form, energy is released,but in organic chemistry i read that when bonds break energy is released.This does not sound right.Any help would be appreciated.
Thanks

[Winga]

Any example?

[zahc]

Hi,ok heres an example, when the atp bond breaks it releases energy,but then i read that when bonds form their release energy.So how does does atp release energy if it breaks? See the confusion?

[zahc]

In other words how can energy be stored in bonds if creating bonds releases energy and breaking bonds requires energy?

[arnyk]

Try this http://www.newton.dep.anl.gov/askasci/gen99/gen99928.htm

[Mitch]

Hi,ok heres an example, when the atp bond breaks it releases energy,but then i read that when bonds form their release energy.So how does does atp release energy if it breaks? See the confusion?

Energy being released from bonds breaking? Energy is released if delta H is less then 0, it is absorbed if delta H is more then 0. Bonds do not exist in a vacuum, the reactants and products need to be analyzed when speaking of energy.

[Winga]

You need to find out all the energies required for bond breaking of all reactant species and energies releasesd from bond formation of all product species.

Then, compare the energy difference.

[Borek]

Energy is released if delta H is greater than 1, it is absorbed if delta H is less than 1.

1 or 0?

[Mitch]

Thanks for the catch Borek. It would be zero. Man, I was off yesterday.

[zahc]

What is delta H? Sorry im a beginner

[lemonoman]

Delta H is the Change in Enthalpy for a chemical process.  It's been defined as, "The sum of the internal energy of matter" (http://en.wikipedia.org/wiki/Enthalpy) - which means, ina VERY simpplified way, it's the sum of the bond energies.

Energy is stored in bonds.  The bonds themselves are a combination of repulsive and attractive forces, which roughly aer equal to each other when the atoms are at the regular bond length.

Delta H is, of course, equal to H_final - H_initial

If you do an internet search of Enthalpy then you'll get more information than you need.  But it'll help out your sresearch skills   Enjoy!

[lemonoman]

Energy being released from bonds breaking? Energy is released if delta H is greater than 1, it is absorbed if delta H is less than 1. Bonds do not exist in a vacuum, the reactants and products need to be analyzed when speaking of energy.

Now I'm confused too.  We've agreed that it should have been 0, but now I'm wondering about the math too...I'm pretty sure:

Delta H = H_final - H_initial

For a reaction in which energy is ABSORBED:
H_final > H_initial     (higher internal energy at completion)
then H_final - H_initial > 0
hence Delta H > 0

Endothermic Reactions have Delta H > 0
Exothermic Reactions have Delta H < 0

Feedback/Input/Corrections/Slander is welcomed !  

[Mitch]

re-edited my post once again.

[xiankai]

delta H is more commonly seen as a triangle followed by H, as the triangle is the greek symbol for delta