Equilibrium

Question 1

What is equilibrium?

Answer 1

A reaction that has the same rate for the forward and reverse reaction and the concentrations of the products and reactants is constant.

Question 2

How do you tell equilibrium from a graph?

Answer 2

When the reactant and product concentration plateau and approach a horizontal line.

Question 3

How do the concentrations of the products and the reactants change in a reaction?

Answer 3

As the product concentration increases so when the product yield grows the reactant concentration decreases as they are being consumed.

Question 4

What is a steady - state?

Answer 4

When the concentrations of the reactants and products are constant not necessarily the same as each other but they are not changing.

Question 5

What is the dynamic equilibrium?

Answer 5

When the rate of the forward and reverse reaction is the same.

Question 6

What is the equilibrium constant?

Answer 6

This is the rate of the reaction that depends on the temperature and is specific to the reaction not the mechanism.

Question 7

What do you exclude when calculating K?

Answer 7

Any pure liquids, solids, or gases.

Question 8

Which values of K favor the products?

Answer 8

When K > 1.

Question 9

Which values of K favor the reactants?

Answer 9

When K < 1.

Question 10

What is a reaction quotient?

Answer 10

The rate of the reaction at any point in time of the reaction taking place.

Question 11

How do you know that the equilibrium is taking place based on the reaction quotient?

Answer 11

Equilibrium occurs when the Qc is constant therefore Qc = K.

Question 12

How is K different from Qc?

Answer 12

K is the rate at which the reaction takes place at equilibrium while Qc is the rate at which the reaction takes place at any point in time.

Question 13

How do you know the direction of the reaction from the Qc value?

Answer 13

When Qc < K the reaction is in the forward direction.

When Qc > K the reaction is in the reverse direction.

Question 14

What happens when Qc = K?

Answer 14

The reaction is in equilibrium.

Question 15

What is an ICE table?

Answer 15

This is a method of organizing the amount or the concentration of the reactants and products of a reaction ONLY mol or mol/L.

Question 16

How do you build an ICE table?

Answer 16

The first row is the starting amounts so it is the INITIAL.

The second row is the amount that is reacting that is your CHANGE which is represented by X and if a substance is being consumed then = -X and if a substance is being added then = +X and the coefficient in front of the X is impacted by the coefficient of the balanced reaction.

The third row is the amount at the end which is EQUILIBRIUM.

Question 17

What happens in a “mixing reaction?”

Answer 17

The reaction is a dilution so the initial concentration has to change using the equation C1V1 = C2V2 and this can only be used when you are looking at the student mixes the solutions.

Question 18

What is Le Chatellier’s Principle?

Answer 18

The idea is that if a stressor impacts the concentration of the substances the concentration will return back to equilibrium.

Question 19

What happens when the volume decreases?

Answer 19

The side with fewer moles is favored.

Question 20

What happens when the volume increases?

Answer 20

The side with more moles is favored.

Question 21

What happens when the pressure increases?

Answer 21

The volume has decreased so look at the side with fewer moles.

Question 22

What happens when the pressure decreases?

Answer 22

The volume has increased so look at the side with more moles.

Question 23

What happens when an inert gas is added?

Answer 23

When an inert gas is added the volume does not change as stated by the ideal gas law. However, the total pressure does change because there are more moles in total. Although, the partial pressures do not change because the individual amounts of the substances do not change.

Question 24

What is an endothermic reaction?

Answer 24

This reaction absorbs the heat thus it is a reactant.

Question 25

What is an exothermic reaction?

Answer 25

This reaction releases the heat thus it is a product.

Question 26

What happens when the temperature changes?

Answer 26

In accordance with Le Chatilier’s Principle, the reactants and products will change in concentration in order for equilibrium to take place thus the Q value will change.