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Flashcards in Kinetics and Equilibria Deck (17):

What is the rate of reaction?

The change in concentration of reactants over time.`


What is the rate equation?

Rate = k[A]^a[B]^b


What are the superscripts in the rate equation?

The orders of reaction with respect to that reactant.


What is the overall order of a reaction?

The sum of the each reactant's superscript.


How does increasing the temperature of a reaction affect the rate constant? Why does this change affect the rate?

The rate constant increases with temperature. This is because the number of collisions increases because the particles are moving faster, and the energy of those collisions is higher, increasing the likelihood that a collision will have enough energy for a reaction to occur.


What is the initial rates method used for?

Calculating the orders with respect to each reactant.


What is the initial rate of reaction?

The rate of reaction at time = 0


What is the initial rates method?

Repeating a reaction several times using different initial concentrations of reactant. Each repeat involves the changing of only one reactant's concentration at a time. Calculate the initial rate of reaction using a conc. reactants vs. time graph, then compare how altering the concentration of a reactant affects the initial rate of reaction.


What is the rate determining step?

The slowest step in a multi-step reaction.


How is it possible to determine which step in a reaction is rate-determining?

By cross-checking the rate equation against the given step. If the reactants in the step all appear in the rate equation in the correct molecule number, then it is the rate-determining step.


What is the order of reaction with respect to a reactant?

The number of molecules of that reactant that are in the rate-determining step.


What is the equilibrium constant?

The ratio between the concentration of products and reactants for a reaction at equilibrium.


What is an expression for the equilibrium constant for the reaction aA + bB dD + eE?



What is Le Chatelier's principle?

A change in concentration, pressure or temperature will cause the equilibrium to shift position to counteract the change.


What is the only condition change that affects the value of Kc?

A change in temperature.


What condition changes do not affect the equilibrium constant?

Altering concentrations or pressure, and the addition of a catalyst.


Why do catalysts not affect the equilibrium constant or the position of an equilibrium?

Because they only serve to increase the rate of reaction in both the forward and reverse directions - the equilibrium is simply attained more quickly.