Energy changes in Reactions :
1-
Summary
exothermic :
:
C- reactants
SH Ot '
C- products
chemical thermal energy
definitions : pot .
energy >
reaction
energies
"
i. e combustion respiration
The heat of the reaction : is the of chemical potential of Oct)
SH net
charge energy a
system .
☐µ
'
Exothermic reactions :
into thermal
2 '
exothermic : E reactants C- products
are reactions which transfer potential energy energy .
'
thermal potential E-
Energy energy Chem
Endothermic reactions :
are reactions which transfer thermal into potential
energy .
.
i. e photosynthesis
energy required
Activation : is the minimum to start a chemical reaction
energy
.
- \
The activated complex :
is a
temporary transition state between the reactants & products . if the forward reaction is exothermic
-
A is substance that increases the rate of the reaction but remains then the
catalyst : a reverse reaction is endothermic
unchanged at the end of the reaction .
i. e add heat to start it remove heat
chemical Reactions :
É way )
to take it back .
the other .
"
absorbed
breaking bonds
energy
=
endothermic
•
released
forming bonds
energy exothermic
=
Hydrogen test
'
stronger bonds :
more
energy needed to break & more
energy when formed .
i. eztlz +02 21-120
É activated
Exothermic reactions : E r comp
. activation
chemical energy stored in bonds & is released as heat .
s energy r
- -
- heat released
or
> , \
. O
Energy !
,
transferred from the system to the s
surroundings .
o
energy , \
C reactants)
.
g-
Temperature of the
system increases .
I heat of
É reaction
'
indicated as H * in
grade 11 . . .
§ energy
(products)
&
'
physical change :
freezing ; condensation re sublimation deposition .
dissolution :
certain ionic compounds when dissolved release heat .
Reaction progress
• '
)
'
lot of heat
explosions producing i. e combustion
:
Chemical reactions a
OR cellular respiration hydrogen test : ZH t Oz -
2h20 ☐µ = -
zgskjmol
-1
Electrolysis of water
i. e 21-120 21-121-02
activated complex
É
-
Z
Endothermic Reactions :
E
heat released
"
" "
'
heat is absorbed & stored in chemical bonds .
of activation / l
energy
Cproducts)
.
z energy /
s
transferred from the surrounding into the of
energy system . o heat
reaction
. g-
temperature of
system decreases .
s energy o
o
( reactants )
§
"
0
indicated as H * in
grade 11 . . .
&
1
physical change :
melting ; evaporation sublimation .
Reaction progress
dissolution : certain ionic compounds when dissolved absorb heat .
'
chemical reactions : photosynthesis & electrolysis i. e water : 21-120 21-121-02 SH =
28s KJ moi
.
'
1-
Summary
exothermic :
:
C- reactants
SH Ot '
C- products
chemical thermal energy
definitions : pot .
energy >
reaction
energies
"
i. e combustion respiration
The heat of the reaction : is the of chemical potential of Oct)
SH net
charge energy a
system .
☐µ
'
Exothermic reactions :
into thermal
2 '
exothermic : E reactants C- products
are reactions which transfer potential energy energy .
'
thermal potential E-
Energy energy Chem
Endothermic reactions :
are reactions which transfer thermal into potential
energy .
.
i. e photosynthesis
energy required
Activation : is the minimum to start a chemical reaction
energy
.
- \
The activated complex :
is a
temporary transition state between the reactants & products . if the forward reaction is exothermic
-
A is substance that increases the rate of the reaction but remains then the
catalyst : a reverse reaction is endothermic
unchanged at the end of the reaction .
i. e add heat to start it remove heat
chemical Reactions :
É way )
to take it back .
the other .
"
absorbed
breaking bonds
energy
=
endothermic
•
released
forming bonds
energy exothermic
=
Hydrogen test
'
stronger bonds :
more
energy needed to break & more
energy when formed .
i. eztlz +02 21-120
É activated
Exothermic reactions : E r comp
. activation
chemical energy stored in bonds & is released as heat .
s energy r
- -
- heat released
or
> , \
. O
Energy !
,
transferred from the system to the s
surroundings .
o
energy , \
C reactants)
.
g-
Temperature of the
system increases .
I heat of
É reaction
'
indicated as H * in
grade 11 . . .
§ energy
(products)
&
'
physical change :
freezing ; condensation re sublimation deposition .
dissolution :
certain ionic compounds when dissolved release heat .
Reaction progress
• '
)
'
lot of heat
explosions producing i. e combustion
:
Chemical reactions a
OR cellular respiration hydrogen test : ZH t Oz -
2h20 ☐µ = -
zgskjmol
-1
Electrolysis of water
i. e 21-120 21-121-02
activated complex
É
-
Z
Endothermic Reactions :
E
heat released
"
" "
'
heat is absorbed & stored in chemical bonds .
of activation / l
energy
Cproducts)
.
z energy /
s
transferred from the surrounding into the of
energy system . o heat
reaction
. g-
temperature of
system decreases .
s energy o
o
( reactants )
§
"
0
indicated as H * in
grade 11 . . .
&
1
physical change :
melting ; evaporation sublimation .
Reaction progress
dissolution : certain ionic compounds when dissolved absorb heat .
'
chemical reactions : photosynthesis & electrolysis i. e water : 21-120 21-121-02 SH =
28s KJ moi
.
'
