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29 Cards in this Set
- Front
- Back
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what is chemical equilibrium |
when the forward and reverse rates of reaction are equal and the concentrations of the products and reactants are constant |
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what is physical equilibrium |
when the phases are in equilibrium rate of changing into one phase is same as rate of changing back phase |
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what is the equilibrium constant |
when a reaction is in equilibrium, the concentrations of the reactants and products, to power of their stoichiometric coefficients, will produce a constant = the equilibrium constant |
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what factors is the equilibrium constant dependent upon |
temperature will change with temperature |
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what is teh law of mass action |
for a certain temperature, a certain reaction, that is reversible, at equilibrium the ratio between the reactant and products is a constant |
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what does the K equilibrium constant tell you about what concentrations are favored - where teh equilibrium lies |
if K is greater than one, greater concentrations of products are present than reactants, at equilibirum if K = 1, products and reactants same concentrations at equilibrium if K less than one, greater concentrations of reactants are present at equilibrium |
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what are very small and very large Ks |
greater than 10 = much larger K values less than 0.1 = very small K values |
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what is a homogeneous equilibrium |
the reaction at equilibrium - the reactants and products are the same phase |
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what is Kp |
the equilibrium constant for gaseous reactions - in terms of partial pressure of reactants and products |
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how is Kp related to Kc? |
Kp = Kc(RT)^change in n change in n = moles of product - moles of reactant |
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does Kc have units |
yes but we don't ever include them |
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what is heterogenous equilibria |
the reactants and products of an equilibrium reaction is in different phases |
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what phases are not included in the equilibirum constant and why? |
solids and liquids are not included in the equilibrium constant since they don't change volume/molar concentrations much throughout the reaction thus no need to include, cosnidered part of the constant |
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what is the equilibrium constant for an overall reaction - combination of multiple reactions |
multiply the equilibirium constants to get the overall equilibrium constant |
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what happens to the equilibrium constant when the reaction is reversed |
to write it for the reverse reaction, divide 1 by the Kc of the forward reaction |
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how to write the equilibrium constant if the reaction is multiplied by a coefficient |
raise the Kc to the power of the stoichiometric coefficient |
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relationship between k rate constant and K equilibrium constant - for a reaction at equilibrium |
K = kf/kr both are constant at a certain temperature meaning that K is also constant at a certain temperature |
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orders of reactants for elementary steps of a reaction |
orders of reactants = to the stoichiometric coefficients of reactants in an elementary reaction but NOT the case for a multi step reaction's overall equation does not necessarily equal to the rate law's order of reactants |
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what is Q |
the ratio between concentrations of products and reactants when the reaction is NOT at equilibrium |
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comparing Q and Kc |
if Q is less than Kc = too much reactants, will go towards products, to the right if Q is = to Kc, at equilibrium, won't shift concentrations anymore if Q is greater than Kc, then too much products, will make more reactants, go to the left |
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what are the four factors that can affect equilibrium |
-temperature concentration volume pressure |
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what can be done to a reaction but not affect equilibrium/the equilibrium constant |
adding a catalyst changes reaction rate both forward and back but does not shift the equilibrium or change the equilibrium constant |
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what does le chatelier's principle state |
that when stress is applied to a system in equilibrium, the system will adjust, to reach a new equilibrium |
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how does change in concentration affect equilibrium |
adding a reactant = shift to teh right to make more product adding a product = shift to the left to make more reactant taking away a reactant = shift to the left to make more reactant taking away a product = shift to the right to make more product |
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are liquids, solids or aqueous solutions affected by change in pressure and volume? |
no, only gases so changes in pressure and volume will only affect gases in equilibrium equations since they affect concentration of the gases |
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what happens to reactions in equilibrium when pressure is increased/volume decreased or when pressure is decreased/volume increases? |
-when pressure increases/volume decreases = reaction favors less moles when pressure decreases/volume increases = favors more moles |
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what happens to equilibrium when there is a change in temperature |
first depends on whether endothermic or exothermic a temperature decrease favors the exothermic side WHEN WRITING THE HEAT - heat can be ONLY ON ONE SIDE, left to right is the direction of the CHANGE IN H |
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how does a catalyst work |
it lowers the activation energy increases the rate of a reaction helps teh system reach equilibrium sooner does not perturb equilibrium does not change the equilibrium constant does not affect what concentrations will be equilbrium |
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only temperature |
can change the VALUE of teh equilibrium constant not concentration, not volume, not pressure not catalyst |
