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Rate
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- ΔReactants / Δt = Δproducts / Δt
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Reactants are negative
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Collision Theory
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states that particles must collide for a reaction to occur, and must have the right orientation and enough energy
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Activated Complex
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a complex that exists very briefly in the time between the breaking down of reactants and forming of products
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Activation Energy
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the minimum amount of energy needed to form the activated complex
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Exothermic Reaction
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a reaction that releases energy; the products end up having less energy that the reactants
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Endothermic reaction
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a reaction that must absorb enough energy to overcome the energy barrier; the products have more energy at the end
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Factors that affect the rate
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catalysts - the nature of the substances - Concentration - Surface Area - Temperature
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Characteristics of equilibrium
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1- fixed ratio, 2- closed system, 3-fixed temp, 4- dynamic equilibrium
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Le Chatelier's Principle
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a change in one variable that describes a system produces a shift in the position of the equilibrium, countering the change
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Effects of Changing Concentration:
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higher reactant concentration = reaction shifts to the right, and vice versa
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Effects of Changing Temperature
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adding heat to and exothermic reaction = more reactants; adding heat to an endothermic reaction = more products
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Effects of Changing Pressure and Volume
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Higher pressure + lower volume = lower number of moles; lower pressure + higher volume = more moles
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if the number of moles are equal on both sides, pressure and volume will have no effect
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Rate Law
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R = k [A]x [B]y
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Order of the reaction
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x+y
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Rate Constant (k)
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is only affected by temp
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Rate Constant Units
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s-1 , L/mol.s , L2/mol2.s
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A and B are the molar concentrations of reactants; the rate is directly proportional to the concentrations
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the coefficients are the exponents
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Complete Reaction
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when reactants change to products (→)
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Reversible reaction
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can go both ways (⇆)
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Equilibrium
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when the rate of the forward reaction equals the rate of the backwards one
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Chemical Equilibrium Law
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states that at a certain temperature, the ratio of the reactants and products can remain constant
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for aA + bB = cC +dD
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Chemical Equilibrium Law Formula
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K eq = [C]c[D]d / [A]a[B]b
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if K eq > 1, the products have a higher concentration, if K eq < 1 the reactants have a higher concentration
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Homogeneous Equilibrium
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when the reactants and products are in the same state of matter
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Heterogeneous Equilibrium
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when the reactants and products are in multiple states (the pure solid and liquids are removed from the equation)
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K eq is directly proportional to temp id the equation is:
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endothermic
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K eq is inversely proportional to temp id the equation is:
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exothermic
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catalyst
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increases the speed at which a reaction reaches equilibrium, but does not change the equilibrium
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K sp = solubility product constant
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Q sp = ionic product
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if K sp > Q sp
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unsaturated, no precipitate
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if K sp = Q sp
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saturated, no precipitate
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if K sp < Q sp
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saturated, precipitate is formed
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K eq is directly proportional to temp id the equation is:
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endothermic
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K eq is inversely proportional to temp id the equation is:
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exothermic
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