15. Reversible Reactions
Let’s look at
another example –
favourite one in
the exams!
The Thermal
Decomposition
of ammonium
chloride,
NH4Cl
16. Reversible Reactions
NH4Cl NH3 + HCl
Heat
Water in
and out
Solid ammonium
chloride
Solid ammonium
chloride
Ammonia and
HCl gases
17. Reversible Reactions
NH4Cl NH3 + HCl
Heat
Water in
and out
Solid ammonium
chloride
Solid ammonium
chloride
Ammonia and
HCl gases
1. When heated. Ammonium
chloride splits up into
ammonia gas and hydrogen
chloride gas.
18. Reversible Reactions
NH4Cl NH3 + HCl
Heat
Water in
and out
Solid ammonium
chloride
Solid ammonium
chloride
Ammonia and
HCl gases
1. When heated. Ammonium
chloride splits up into
ammonia gas and hydrogen
chloride gas.
2. As these gases cool on the
bottom of the flask, they
recombine to form solid
ammonium chloride again.
19. Reversible Reactions
NH4Cl NH3 + HCl
Heat
Water in
and out
Solid ammonium
chloride
Solid ammonium
chloride
Ammonia and
HCl gases
1. When heated. Ammonium
chloride splits up into
ammonia gas and hydrogen
chloride gas.
2. As these gases cool on the
bottom of the flask, they
recombine to form solid
ammonium chloride again.
3. This is a good example of
a reversible reaction
because the products
recombine to easily form
the original reactants.
23. Reversible Reactions and
Closed Systems
A + B C + D
A and B will be combining to form C and D,
while at the same time C and D will be
combining to form A + B.
24. Reversible Reactions and
Closed Systems
A + B C + D
A point will eventually be reached when the
rate of the forward reaction is equal to the
rate of the backward reaction.
26. Reversible Reactions and
Closed Systems
Temperature and equilibria
A + B C + D
If the forward reaction (i.e. going from left to right) is
ENDOTHERMIC and heat energy is taken in ……..
27. Reversible Reactions and
Closed Systems
Temperature and equilibria
A + B C + D
If the forward reaction (i.e. going from left to right) is
ENDOTHERMIC and heat energy is taken in ……..
Then if the
temperature is
increased.
28. Reversible Reactions and
Closed Systems
Temperature and equilibria
A + B C + D
If the forward reaction (i.e. going from left to right) is
ENDOTHERMIC and heat energy is taken in ……..
Then if the
temperature is
increased.
The yield of
products is
increased, and
more heat is
taken in.
29. Reversible Reactions and
Closed Systems
Temperature and equilibria
A + B C + D
If the forward reaction (i.e. going from left to right) is
ENDOTHERMIC and heat energy is taken in ……..
Then if the
temperature is
decreased
30. Reversible Reactions and
Closed Systems
Temperature and equilibria
A + B C + D
If the forward reaction (i.e. going from left to right) is
ENDOTHERMIC and heat energy is taken in ……..
Then if the
temperature is
decreased.
The yield of
products is
decreased, and
less heat is
taken in.
31. Reversible Reactions and
Closed Systems
Temperature and equilibria
A + B C + D
If the forward reaction (i.e. going from left to right) is
EXOTHERMIC and heat energy is given out……..
32. Reversible Reactions and
Closed Systems
Temperature and equilibria
A + B C + D
If the forward reaction (i.e. going from left to right) is
EXOTHERMIC and heat energy is given out……..
Then if the
temperature is
increased.
33. Reversible Reactions and
Closed Systems
Temperature and equilibria
A + B C + D
If the forward reaction (i.e. going from left to right) is
EXOTHERMIC and heat energy is given out……..
Then if the
temperature is
increased.
The yield of
products is
decreased, and
less heat is given
out.
34. Reversible Reactions and
Closed Systems
Temperature and equilibria
A + B C + D
If the forward reaction (i.e. going from left to right) is
EXOTHERMIC and heat energy is given out……..
Then if the
temperature is
decreased.
35. Reversible Reactions and
Closed Systems
Temperature and equilibria
A + B C + D
If the forward reaction (i.e. going from left to right) is
EXOTHERMIC and heat energy is given out……..
Then if the
temperature is
decreased.
The yield of
products is
increased, and
more heat is
given out.
41. Reversible Reactions and
Closed Systems
Pressure and equilibria Increasing the pressure will
push the reaction in the
direction of fewer molecules
42. Reversible Reactions and
Closed Systems
Pressure and equilibria Increasing the pressure will
push the reaction in the
direction of fewer molecules
Increased pressure
43. Reversible Reactions and
Closed Systems
Pressure and equilibria Increasing the pressure will
push the reaction in the
direction of fewer molecules
Decreased pressure
44. End of Section 4 Lesson 4
In this lesson we have covered:
Reversible reactions
Reversible reactions in closed systems
