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topic_7_equilibrium_7.1_17.1.pptx - IB CHEMISTRY Topic 7...

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Topic 7 EquilibriumlevelHigherlevelIB CHEMISTRY
7.1 EquilibriumOBJECTIVES• A state of equilibrium is reached in a closed system when the rates of the forwardand reverse reactions are equal.• The equilibrium law describes how the equilibrium constant (Kc) can be determinedfor a particular chemical reaction.• The magnitude of the equilibrium constant indicates the extent of a reaction atequilibrium and is temperature dependent.• The reaction quotient (Q) measures the relative amount of products and reactantspresent during a reaction at a particular point in time. Q is the equilibrium expressionwith non-equilibrium concentrations. The position of the equilibrium changes withchanges in concentration, pressure, and temperature.• A catalyst has no effect on the position of equilibrium or the equilibrium constant.• The characteristics of chemical and physical systems in a state of equilibrium.• Deduction of the equilibrium constant expression (Kc) from an equation for ahomogeneous reaction.• Determination of the relationship between different equilibrium constants (Kc) forthe same reaction at the same temperature.• Application of Le Châtelier’s principle to predict the qualitative effects of changes oftemperature, pressure and concentration on the position of equilibrium and on thevalue of the equilibrium constant.
In an ordinary reaction; all reactants endup as products; there is 100%conversionConcentration change in a reactionAs the rate of reaction is dependant on the concentration of reactants... theforward reaction starts off fastbutslows as the reactants get lessconcentratedFASTEST ATTHE STARTSLOWSDOWN ASREACTANTSARE USEDUPTOTALCONVERSION TOPRODUCTSTHESTEEPERTHEGRADIENT, THEFASTERTHEREACTION
Haber Process example
Initially, there is no backward reaction but, as products form, it speeds up andprovided the temperature remains constant there will come a time when the backwardand forward reactions are equal and opposite; the reaction has reached equilibrium.In an equilibrium reaction, not all thereactants end up as products; there is not a100% conversion.BUT IT DOESN’T MEAN THE REACTIONIS STUCK IN THE MIDDLEFASTEST AT THE STARTNO BACKWARD REACTIONFORWARD REACTION SLOWS DOWNAS REACTANTS ARE USED UPBACKWARD REACTIONSTARTS TO INCREASEAT EQUILIBRIUM THE BACKWARDAND FORWARD REACTIONS AREEQUAL AND OPPOSITEEquilibrium reactions
IMPORTANT REMINDERS

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Term
Spring
Professor
carlson
Tags
Chemistry, Equilibrium, Chemical reaction, Kc

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