202-NYB-05 Chapter 13 - Lecture

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CHEMISTRY OF SOLUTIONS
Chapter 13 Lecture

202-NYB-05




13.1 Equilibrium:
• système fermé
CHEMICAL EQUILIBRIUM (sauf pour solide)
• Propriétés
macroscopiques
constantes
Many reactions do not go to completion; they (couleur, pression,
concentration,
stop at an intermediate state between products température, pH et
and reactants n)
• Combustion = pas
Brown Colourless d’équilibre car
reaction complète
non réversible
NO2(g) + NO2(g) N2O4(g)

equilibrium

rateof rateof
forward reverse
reaction reaction
2




1%

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13.1

CHEMICAL EQUILIBRIUM
Facteurs qui
in uence l’équilibre
The state where the concentrations of all the reactants
and products remain constant.
Brown Colourless
NO2(g) + NO2(g) ooooo N2O4(g)
or
Rome




3




13.1

CHEMICAL EQUILIBRIUM

NO2(g) + NO2(g) 2O4(gN) N2O4(g)

Chemical equilibrium is a DYNAMIC process; where the
reaction occurs in both directions continually, but the
proportions of product and reactant remain constant




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2%



fl

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13.1

CHEMICAL EQUILIBRIUM
Consider:

H2O(g) + CO(g) H2(g) + CO2(g)
Equilibrium


[CO2] or [H2]
[reactants]
never goes to
zero
the
cuz reaction
end
doesn't [CO] or [H2O]


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13.1

CHEMICAL EQUILIBRIUM
Why does equilibrium occur?
H2O(g) + CO(g) H2(g) + CO2(g)
H2O(g) + CO(g) H2(g) + CO2(g)




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3%

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13.1

CHEMICAL EQUILIBRIUM

Although no changes are perceivable under equilibrium
conditions… reactions are continually occurring

A+B C+D

•equilibrium lies to the right
•equilibrium lies to the left
•If the reaction favours
•If the reaction favours
the products.
the reactants Teansitrequires
less than
energy
theotherone 7




CHEMICAL EQUILIBRIUM
Whether an equilibrium reaction lies to the right or to
the left depends on several factors:

If lies 1. Initial concentrations
on the 2. Relative energies of reactants and products
right or
left 3. Relative degree of organization of reactants and
products




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