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ap chem > unit 9 > Flashcards

unit 9 Flashcards

1
Q

reversible reaction

A

a reaction that can proceed in both the forward and reverse directions

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2
Q

dynamic equilibrium

A

the rate of the reverse reaction equals the rate of the forward reaction

(this does not mean that [reactants] and [products] are equal to one another at equilibrium)

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3
Q

Equilibrium constant (K)

A

Quantifies the relationship between [reactants] and [products] at equilibrium

K = [products]/[reactants]

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4
Q

significance of large K
(K&raquo_space; 1)

A

forward reaction is favored
-K lies far to right
-high [product] and low [reactant] at equilibrium
-forward reaction proceeds essentially to completion

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5
Q

significance of small K
(K &laquo_space;1)

A

-reverse reaction is favored
-K lies far to left
-Low [product] and high [reactant] at equilibrium
-Forward reaction does not proceed very far

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6
Q

if you reverse the equation, _ K

A

invert

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7
Q

what happens to K when you multiply the coefficients in the equation?

A

raise K by the same factor you multiplied the coefficients

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8
Q

what do you do to K when you add two or more individual chemical equations to each other to obtain an overall equation?

A

multiply K’s from all equations

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9
Q

What is dynamic equilibrium? Why is it called dynamic?

A

Rate of the forward reaction = rate of the reverse reaction

Even though [reactants] and [products] remain constant, both the forward and reverse reactions are occurring-reactants and products form at the same rate that they are depleted

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10
Q

What is the significance of the equilibrium constant? What does a large equilibrium constant tell us about a reaction? A small one?

A

Indicates if the forward reaction (large K) or the reverse reaction (small K) is favored

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11
Q

concentration of gas equation

A

n/V = P/RT

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12
Q

pressure of a gas and concentration proportion

A

direct

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13
Q

Kc

A

equilibrium constant expressed in terms of concentrations of reactants and products

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14
Q

Kp

A

equilibrium constant for gaseous reactions, expressed in terms of partial pressure in atm

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15
Q

is the partial pressure of a gas in atm the same as the molar concentration of that gas?

A

no

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16
Q

Kc and Kp are only equal when

A

there is no change in the number of gas phase particles during the reaction

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17
Q

gas particle change equation

A

Kp = Kc (RT)^∆n

∆n = mol products - mol reactants

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18
Q

Explain the difference between Kc and Kp. For a given reaction, how are the two constants related?

A

Kc is the equilibrium constant with respect to concentration in molarity

Kp is the equilibrium constant for gaseous reactions in terms of partial pressures

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19
Q

why don’t pure liquids/solids included in equilibrium expressions?

A

their concentrations do not change in the course of the reaction

they’re incorporated into values of Kc or Kp

ONLY INCLUDE GASES IN EQUILIBRIUM EXPRESSION

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20
Q

The equilibrium [reactants] and [products] can vary depending on

A

their initial concentrations

21
Q

the equilibrium constant is always constant at

A

any temp, regardless of initial concentrations

22
Q

reaction quotient (Qc)

A

gauges the progress of a reaction relative to equilibrium, when the reaction mixture is not at equilibrium and contains reactants and products

-same as equilibrium constant, doesn’t need to be at equillibrium

23
Q

differences between Kc and Qc:

A

-Kc has only one value and specifies relative amounts of reactants and products at equilibrium
-Qc depends on the current state of the reaction and has many different values as the reaction proceeds

24
Q

what is the value of Qc when there are only reactants?

A

0

25
Q

what is the value of Qc when there are only products?

A

infinity

26
Q

what is the value of Qc when there are equal amounts of products and reactants?

A

1

27
Q

what happens when Q < K?

A

Reaction goes to the right (towards products)

28
Q

what happens when Q > K?

A

Reaction goes to the left (towards reactants)

29
Q

what happens when Q = K?

A

equilibrium

30
Q

when the equilibrium constant is small, will the reaction proceed far?

A

no

31
Q

Le Chatelier’s Principle

A

When a chemical system at equilibrium is disturbed, the system shifts in a direction that minimizes the disturbance.

A chemical system can be disturbed by changing [reactant] or [product], changing volume or pressure and changing temperature.

32
Q

volume and pressure proportion

A

inversely related

33
Q

if a system is at equilibrium, what happens when you decrease the volume?

A

the reaction shifts in the direction that has fewer moles of gas particles

34
Q

if a system is at equilibrium, what happens when you increase the volume?

A

the reaction shifts in the direction that has greater moles of gas particles

35
Q

does adding an inert gas to the mixture have an effect on the equilibrium?

A

no

36
Q

Increasing the concentration of one or more reactants (makes Q < K) causes the reaction to shift to the

A

right (toward products)

37
Q

Increasing the concentration of one or more products (makes Q > K) causes the reaction to shift to the

A

left (toward reactants)

38
Q

Decreasing the concentration of one or more reactants (makes Q > K) causes the reaction to shift to the

A

left (toward reactants)

39
Q

Decreasing the concentration of one or more products (makes Q < K) causes the reaction to shift to the

A

right (toward products)

40
Q

is a reaction has the same number of gas particles on both sides, what happens when the volume changes?

A

nothing

41
Q

what happens when you increase the temp in an exothermic reaction?

A

reaction shifts left
K decreases

42
Q

what happens when you decrease the temp in an exothermic reaction?

A

reaction shifts right
K increases

43
Q

what happens when you increase the temp in an endothermic reaction?

A

reaction shifts right
K increases

44
Q

what happens when you decrease the temp in an endothermic reaction?

A

reaction shifts left
K decreases

45
Q

do catalysts affect the position of equilibrium?

A

no

46
Q

solubility product constant (Ksp)

A

equilibrium constant for dissolution of an ionic compound

(measure of solubility)

47
Q

molar solubility

A

solubility in units of mol/L

-only one value at a given temp
-can have different values in different types of solutions

48
Q

what is lower, the solubility of an ionic compound in a solution containing a common ion or the solubility of an ionic compound in water?

A

in solution containing a common ion

49
Q

what happens when you add a soluble salt to a reaction that contains an insoluble salt?

A

it increases the solubility of the insoluble salt

ap chem (11 decks)

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