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chemical equilibrium - Coggle Diagram
chemical equilibrium
reaction quotient, Q
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obtain by substituting the initial concentrations/partial pressure of reactants and products into equilibrium constant expression
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Q>K, excess of products will react to form reactants to reach equilibrium (more products in reaction mixture initially)
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Q=K, reaction is at equilibrium
Q<K, excess reactants will react to form products to reach equilibrium (more reactants in reaction mixture initially)
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position of equilibrium
equilibrium constant, K is ratio of products to reactants
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if K>1, equilibrium favours products, lies to the right
if K<1, equilibrium favours reactants, lies to the left
degree of association
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alpha=1, complete dissociation (100%)
alpha = x/a
x=change, a=initial concentration or no. of mole
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le Chatelier's principle
according to it, if a chemical system at equilibrium experiences a change in temperature, pressure, or concentration of a reactant or product, the position of equilibrium shifts to partially counteract the effect of the change until a new equilibrium is reached
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effect of concentration
if conc. is increased, equilibrium position shift to direction that tends to reduce that concentration
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new equilibrium achieved but relative amount of reactants & products in equilibrium remains constant
this reduces concentration of reactants added, increase conc. of products
so, concentration has no effect on values of Kc & Kp
effect of temperature
according to le Chatelier's principle when temperature increase, equilibrium position shift in direction of endothermic (absorb heat)
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when temperature decrease, equilibrium shift in direction of exothermic (release heat)
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if temperature increase, rate of both forward and reverse reactions increase but not increase by the same extent
hence, change in temperature will change equilibrium position and Kc & Kp
my formula
if forward reaction is endothermic
temperature increase, Kc increase
temperature decrease, Kc decrease
if forward reaction is exothermic
temperature increase, Kc decrease
temperature decrease, Kc increase
effect of pressure
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how to change pressure (constant temperature, affects equilibrium)
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change external pressure
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external pressure increase, volume decrease and vice versa
external pressure increase, equilibrium position shift in direction that reduce no. of moles of gas to reduce pressure
external pressure decrease, equilibrium position shift in direction that increase no. of moles of gas to increase pressure
add an inert gas (internal pressure) to equilibrium mixture at constant pressure and constant volume
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changes in external pressure will not affect the equilibrium system when total no. of moles of gaseous reactants = total no. of moles of gaseous products (the coefficient of all gaseous stuff in its balanced equation)
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equilibrium constant
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Kp only involves gases
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P is partial pressure of gas (atm, bar, Pa, kPa and others)
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relationship Kc and Kp
PV=nRT
P=(n/V) RT
P=MRT
gas constant, R = 0.08206L atm K^-1 mol^-1
or 0.0821 (same unit)
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equilibrium law
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states that for any equilibrium at a constant temperature, the product of concentrations of products divided by concentrations of reactants, each raised to its power equal to its coefficient in the balanced chemical eq., is a constant (equilibrium constant)
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