Unit 7: Reversible reactions and equilibrium + calculating equilibrium constant

Question 1

When did scientists discover reversible reactions

Answer 1

1803

Question 2

What does it mean for a reaction to be a reversible reaction

Answer 2

The forward reaction and the backward reaction are occurring at the same rate

Question 3

What does equilibrium mean

Answer 3

to be in a state of balance

Question 4

What type of reactions are reversible

Answer 4

insoluble, weak acids, weak bases

Question 5

when does chemical equilibrium occur

Answer 5

when the opposing reactions equal the same rate

Question 6

after equilibrium is reached has the reaction stopped?

Answer 6

No, the reaction has not stopped things are still happening but at the molecular level

Question 7

what reactions are soluble

Answer 7

strong acids, bases and soulble salts

Question 8

what is the Haber Process

Answer 8

nitrogen gas and hydrogen gas react to produce ammonia

Question 9

how do you measure the progress of a reversible reaction

Answer 9

reaction quotient or Qc

Question 10

when can Qc be calculated?

Answer 10

at any point of the reaction because it is not constant

Question 11

what is the equation for the quotient reaction?

Answer 11

[products] / [reactants]

Question 12

what is the reaction quotient now called when equilibrium has been reached?

Answer 12

called the equilibrium constant or Kc

Question 13

Is Kc constant?

Answer 13

Yes Kc is constant

Question 14

what does Kc tell us

Answer 14

product to reaction concentrations once equilibrium has been reached

Question 15

What is Qc dependent on?

Answer 15

The progress of the reaction, that is why it can change over time

Question 16

What happens when Qc has stabilized

Answer 16

equilibrium has been reached

Question 17

Kc =

Answer 17

Qc

Question 18

when can equilibrium occur in a reaction?

Answer 18

it can occur at any point of the reaction, and it is unique to that specific reaction

Question 19

what does equilibrium NOT mean

Answer 19

that the concentrations are the same

Question 20

what does it mean if K>1

Answer 20

the equilibrium favors products

Question 21

what does it mean if K<1

Answer 21

the equilibrium favors reactants

Question 22

what is the equation for the for the inverse of a Kc reaction

Answer 22

1/ Kc

Question 23

On a particle diagram, when can you tell that equilibrium has been reached

Answer 23

the mlcls are still but changing, but the ratio is consistent

Question 24

on a haber process graph, how do you know when reactants are favored

Answer 24

when the reactants are less than the products, and vice versa for the products

Question 25

what should you do when q is smaller than k

Answer 25

when q is smaller than k, then we need to increase the amount of products, and decrease the amount of reactants to increase Q

Question 26

what should you do when q>k

Answer 26

when q is bigger than k, we need to decrease the amount of products and increase the amount of reactants

Question 27

why can’t solids and liquids be included in an equlibibrium expression

Answer 27

they do not have concentrations

Question 28

which states are included in the equilibrium expression

Answer 28

aqueous and gases

Question 29

what changes the Kc value

Answer 29

temperature

Question 30

what should you do if you have a reverse reaction when trying to calculate equilibrium constant

Answer 30

take the inverse of the OG Kc

Question 31

what happens when you multiply a reaction by a factor?

Answer 31

raise the OG Kc to the power of that factor

Question 32

what should you look @ when trying to calculate the Kc value

Answer 32

always look at the first reaction

Question 33

what happens when you combine reactions

Answer 33

multiply the Kc constants

Question 34

what do you use to calculate equilibrium expressions

Answer 34

a rice table

Question 35

what do you do when an initial concentration or pressure is not given

Answer 35

assume it starts at zero

Question 36

what ratio will the changes occur in?

Answer 36

mole to mole

Question 37

what should you do if you don’t know the change or final concentration

Answer 37

use x

Question 38

How can you use Qc in calculating equil. express.

Answer 38

Qc can be used to see the way the reaction is going to shift, and compare with Kc