Endothermic/Exothermic Reactions

ENDO/EXO

In order for any reaction to occur ,
2
things must happen
:




' 1 ㅣ

、


'




" A C ㄹ

A -

B + C B -
、
A-D + C-B
「
D B
'
\


…



1 the bonds
holding the reactants together must break chemical potential energy a
thermal energy
~
the bonds holding the products together must form thermal energy a chemical potential energy
"


, , is the activated complex ->
energy has been released and not yet absorbed >
-
high energy soup


endo/exo come into
play when the amt of
energy released by the
breaking of reactant bonds does not equate to

the amt of energy required to form product bonds


The specific change in
energy is called 'Enthalpy' or the 'heat of the reaction' (OH)
&H =
Eproducts -

Ereactants



A -

号 + C B-

>
- A-D + C-B where did the 20K] ? TO THE ENVIRONMENT
go
100 KJ 80 KJ we feel this as HEAT (thermal energy) :.
exothermic




DH = 80-100 : -2045 EXO : OH 28




A B +
C-D A- D C-B 80K5 from ?
products get
> +
where did the the extra

100 KJ 180 K J FROM THE ENVIRONMENT We feel this as heat being removed it
-

.




COLDER
gets : endothermic




UH =
180 -100 = 80K5 EndO : OH 3O




POTENTIAL ENERGY PROFILES




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