Le Chatheliar Principle - Presentation

8/7/2019 Le Chatheliar Principle - Presentation

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Learning outcomes based on this topic ;

Able to explain the Le Chateliers Principle

can explain the concept of equilibrium in system/reaction

Able to identify the factors that affecting the Le Chateliers Principle

Everyday examples and chemistry examples which obey the concept


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If a c e ical syste at e ili ri is s jecte

t a c a e i c iti s, t e syste ill a j stt re-esta lis i s c a ay as t artially c teract t e i se c a e


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ABOUTABOUTTHETHE PRIN IPLEPRIN IPLE

In chemistry, t e ri ci le is als calleLe Chatelier-Braun Principle

It ca e se to predict the effect of a change

in conditions on a chemical equilibrium

The ri ci le a e after Henry Louis Le ChatelieraKarl Ferdinand Braun ho iscovere it i e e e tly


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FACTORS

CONCENTRATION TEMPERATURE

PRESSURE / VOLUME CATALYST


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Changes in Concentration

N2 (g) + 3H2 (g) 2NH3 (g)

AddNH3

Equili riumshifts left tooffset stress

LeLe ChChteliersteliers PrinciplePrinciple


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Changes in Concentration

Change Shifts the Equilibrium

Increase concentration of product(s) leftDecrease concentration of product(s) ri ht

Decrease concentration of reactant(s)

Increase concentration of reactant(s) ri ht

left

14.5

aA+ bB cC + dD

AddAddRemove Remove


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Changes in Volume and Pressure

A(g) + B(g) C(g)

Change Shifts the Equilibrium

I crease ressure Side ith fe est moles of as

ecrease ressure Side ithmost moles of as

ecrease volumeI crease volume Side ithmost moles of as

Side ith fe est moles of as

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Changes inTemperat re

The effect of cha i the temperatureof equili rium systemsca e predicted from a k owledgeof the heats of reactions

According to the principle', if the temperatureof an equili rium systemis increased, the systemwill adjust to re-esta lish equili rium in such awayas todecrease the temperature

Therefore, in re-esta lishing equili rium the ofendothermic reaction

is favoured as this a sor s heat from the surroundings andwould tendtodecrease the temperature

For exothermic reaction, if the temperatureof the equili rium systemwas reduced, then itwould increase the temperatureof surroundings


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Changes in emperature

Change Exothermic Rx

Increase temperature Kdecreases

Decrease temperature Kincreases

Endothermic Rx

Kincreases

Kdecreases

14.5colder hotter


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Presence of catalyst

Does not changeequilibrium constant,K

Donot shift theposition of equilibrium

* Systemwill achieve equili rium sooner


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The manufacture ofThe manufacture ofAmmoniaAmmonia


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Influence ofInfluence ofpressurepressure in manufacture ofin manufacture of

AmmoniaAmmonia

Small number ofgaseous molecules used to increase the pressure

Higher pressures can tend to increase the rate of the reaction

Inmodern, ammonia process plants operate at highpressures

of about 350 atmopheres


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Contact processContact process


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Le Chatheliar Principle - Presentation