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Flashcards in General Chemistry- Equilibrium Deck (69)
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1

What is Le Chatelier's principle?

CO2(g) + H2O(l) H2CO3(aq) (H+)(aq) + (HCO3-)(aq)

2

What is important to not confuse?

The chemical equilibrium expression for the rate expression

3

Catalysts do what in regards to equilibrium and can't do what?

Catalysts make reactions go faster toward their equilibrium position, but that they can't actually change the equilibrium position or alter the value of keq

4

What are irreversible reactions?

the reaction proceeds in one direction only, the reaction goes to completion, and the maximum amount of product formed is determined by the amount of limiting reagent initially present.

5

What are reversible reaction?

The reaction can proceed in one of two ways: forward (toward the products or "to the right") and reverse (toward the reactants or "to the left")

6

Why do reversible reactions usually not proceed to completion.

The products can react together to reform the reactants.

7

In a reversible reaction, when the system is closed and no reactants are added or removed, the system will what?

The system will eventually settle into a state in which the rate of the forward reaction equals the rate of the reverse reaction and the concentrations of the products and reactants remain constant.

8

What is a dynamic equilibrium?

The forward and reverse reactions are still occurring--they haven't stopped, but they are going at the same rate; thus, there is no net change in the concentrations of the products or reactants

9

what is static equilibrium?

The forward and reverse reactions have stopped

10

What is the generic reversible reaction?

A B

11

What does the generic reversible reaction show?

At equilibrium, the concentrations of A and B are constant (although not necessarily equal), and the reaction A --> B and B --> A continue to occur at equal rates.

12

How can equilibrium be though of as?

A balance between the forward and reverse reactions.

13

What is entropy?

The measure of the distribution of energy throughout a system or between a system and its environment.

14

For a reversible reaction at a given temperature, the reaction will reach equilibrium when what occurs?

The system's entropy--or energy distribution--is at a maximum and the Gibbs free energy of the system is at a minimum.

15

What does the law of mass action state for a generic reversible reaction:
aA + bB cC + dD?

If the system is at equilibrium at a constant temperature, then the following ratio is constant:
keq=([C]^c[D]^d)/([A]^a{B}^b)

16

The law of mass action is actually related to what?

The expression for the rates of the forward and reverse reactions.

17

What are the rates of forward and reverse reactions based on the following one-step reversible reaction
2A B + C?

rate(f)= (kf)[A}^2
Rate(r)=(kr)[B][C]

18

When rate(f)=rate(r), the system is what?

In equilibrium

19

The rate expressions for the forward and reverse reaction equal each other and will look like what?

(kf)[A}^2 = (kr)[B][C] --> (kf)/(kr) = [B][C]/[A]^2

20

What can occur since (kf) and (kr) are both constants?

We can define a new constant (kc)

21

What is the equilibrium constant for a equilibirum equation of (kf) and (kr).

kc and the subscript c indicates that it is in terms of concentration. When dealing with gases, the equilibrium constant is referred to as (kp), and the subscript p indicates that it is in terms of pressure.

22

What is the new equation when using (kc) as the constant instead of (kr) or (kf)?

(kc)= keq = [B][C]/[A]^2

23

Are the concentrations of the reactants and products equal when the forward and reverse reaction reates are equal at equilibrium?

The concentrations of the reactants and products are not usually equal

24

If the concentrations of the reactants and products are not equal, are the forward and reverse reaction rate constants equal?

(kf) and (kr) are not usually equal to each other

25

What is the ratio of (kf) to (kr) in regards to (kc)?

(kc)= Keq= (kf)/(kr)

26

How do you find the equilibrium constant for the overall reaction when the reaction occurs with more than 1 step?

By multiplying the equilibrium constants for each step of the reaction.
The equilibrium constant for the overall reaction is equal to the concentrations of the products divided by the concentrations of the reactants in the overall reaction, with each concentration term raised to the stoichiometric coefficient for the respective species.

27

What would the equation for rate constant be, for the reaction aA + bB = cC + dD

(kc)= [(k1)(k2)(k3)/(k-1)(k-2)(k-3)] = [C]^c[D]^d/[A]^a[B]^b

28

The law of mass action defines what?

The position of equilibrium

29

Equilibrium is only achieved how?

Through time

30

What is the role of the reaction quotient?

To serve as a timer to indicate how far the reaction has proceeded toward equilibrium