Use bond energies to determine δhrxn for the reaction between ethane and chlorine. ch3ch3(g)+cl2(g)→ch3ch2cl(g)+hcl(g)

For this reaction to proceed, the following bond breaking should occur: 

*one C-H bond
* one Cl-Cl bond

After, the following bond formations should occur:
*one C-Cl bond
*one H-Cl bond

Now, add the bond energies for the respective bond energies which can be found in the attached picture. For bond formations, energy is negative. For bond breaking, energy is positive.

ΔHrxn = (1)(413) + (1)(242) + 1(-328) + 1(-431) = -104 kJ

Ifound this on google “laws of chemical combination. it states that matter can neither be created nor destroyed. it stated that a given compound always contains exactly the same proportion of elements by weight.” i hope this you for what your looking for.