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In a chemical reaction, chemical equilibrium is thestate in which the concentrations of the reactants and

products have not yet changed with time. It occursonly in reversible reactions, and not in irreversible

reactions. Usually, this state results when the forwardreaction proceeds at the same rate as the reverse

reaction. The reaction rates of the forward and reversereactions are generally not zero but, being equal, there

are no net changes in the concentrations of thereactant and product. This process is called dynamic

equilibrium.

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Chemical equilibrium occurs when a reaction

and its reverse reaction proceed at the same

rate.

As a system approaches equilibrium, boththe forward and reverse reactions are

occurring.

At equilibrium, the forward and reversereactions are proceeding at the same rate.

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Once equilibrium is achieved, the amount of each reactantand product remains constant.

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In a system at equilibrium, both the forward and reversereactions are being carried out; as a result, we write its

equation with a double arrow.

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Reverse reaction:

2 NO2 (g) N2O4 (g)

Rate law:Rate = kr[NO2]

2

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Therefore, at equilibrium

Ratef= Rater

Kf[N2O4] = kr[NO2]2

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Because pressure is proportional to concentration forgases in a closed system, the equilibrium expression

can also be written

Kp =(PC)

c (PD)d

(PA)a (PB)

b

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From the ideal gas law we know that

PV= nRT

Rearranging it, we get

P= RT

n

V

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Plugging this into the expression for Kp for eachsubstance, the relationship between Kc and Kp

becomes

Kp= Kc(RT)n

WHERE

n = (moles of gaseous product) (moles of gaseous reactant)

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As you can see, the ratio of [NO2]

2 to [N2O4] remainsconstant at this temperature no matter what the initial

concentrations of NO2 and N2O4 are.

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IfK>> 1, the reaction isproduct-favored; productpredominates at equilibrium.

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IfK>> 1, the reaction isproduct-favored; productpredominates at equilibrium.

IfK

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To calculate Q, one substitutes the initial concentrationson reactants and products into the equilibriumexpression.

Q gives the same ratio the equilibrium expression gives,but for a system that is not at equilibrium.

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The system is at equilibrium

IfQ > K,

there is too much product and theequilibrium shifts to the left.

IfQ < K,

there is too much reactant, and theequilibrium shifts to the right.

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If a system at equilibrium is disturbed by a change intemperature, pressure, or the concentration of one ofthe components, the system will shift its equilibrium

position so as to counteract the effect of the

disturbance.

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SO,IN THE ABOVE SLIDES WE STUDIED SOME

BASICS OF CHEMICAL

EQUILIBIRIUM

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THIS WAS ALL ABOUT CHEMICAL EQUILIBIRIUMFROM MY SIDE.I HOPE THAT THE RESPECTED

JUDGES, TEACHERS AND MY FRIENDS LIKE MYEFFORT..

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