chapter 12: Chemical Equilibrium

Question 1

what is a reversible reaction

Answer 1

reaction that can proceed in both the forward and reverse direction

Question 2

what happens as the forward reactions slows

Answer 2

the reverse reaction accelerates and they reach the same rate

Question 3

what is a dynamic /chemical equilibrium

Answer 3

rates of the forward and reverse reaction are equal

Question 4

in chemical equilibrium are the concentrations equaling each other

Answer 4

No, but they remain constant

Question 5

what is the law of mass action

Answer 5

rates of the forward and reverse rxns are equal but not the concentrations

Question 6

who discovered the law of mass action

Answer 6

cato guldberg and peter waage

Question 7

what letter represents the constant

Answer 7

K

Question 8

what will affect K

Answer 8

temperature

Question 9

what is the Kc constant expression

Answer 9

[Products] / [reactants]

Question 10

if the temperature is constant then what happens to Kc

Answer 10

Kc is constant

Question 11

what happens when an equilibrium constant expression is written backward

Answer 11

then you need to find the inverse of the o.g reaction

Question 12

when manipulating K reactions do you multiply or add the ks together

Answer 12

multiply them

Question 13

what do you do when a balanced chem is multiplied by a factor

Answer 13

the equilibrium constant is raised by that factor

Question 14

what is the concentration of gas in a mixture proportional to

Answer 14

the partial pressure

Question 15

what is the constant expressions of Kp

Answer 15

(partial pressure products) / ( partial pressure of the reactants)

Question 16

what can we use to find the pressure in an equation

Answer 16

p=nRT/v

Question 17

what is the number for r

Answer 17

r = 0.08206

Question 18

what is the equation for Kp and Kc

Answer 18

Kp = (RT) ^(change in moles)

Question 19

how do you find the change in moles

Answer 19

( moles of gas product)- (moles of gas reactant)

Question 20

when does Kp = Kc

Answer 20

when the change of moles is 0 ( same # of moles of gas appear on both sides of the balanced chem equation)

Question 21

what is a homogenous equilibria

Answer 21

substances all in the same phase

Question 22

what is a heterogenous equlibria

Answer 22

involves substances that are in different states

Question 23

what states are not involved in an equilibrium reaction

Answer 23

solids and liquids

Question 24

3 reasons its good to know the equilibrium constant

Answer 24

a. ) whether the concentrations represent an equilibrium condition
b. ) the tendency of the reaction to occur
b. ) the equilibrium position that will be achieved

Question 25

what is K constant not related to

Answer 25

the time required to reach the equilibrium

Question 26

what does time depend on

Answer 26

the reaction rate, due to the size of the activation energy

Question 27

if K is greater than 1 what does that mean

Answer 27

the reaction is product favored bc there is a greater concentration of products than reactants

Question 28

if K << 1, what does that mean

Answer 28

the reaction is reactant favored, the concentration of reactants is greater than the

Question 29

what can help us predict the direction of the reaction

Answer 29

Qc

Question 30

what will the system do if one of the reactants or products is 0

Answer 30

it will shift to produce the missing component

Question 31

how can Qc be found

Answer 31

substitute the initial reactant and product concentrations or partial pressures into an equilibrium-constant expression

Question 32

what does it mean if q =k

Answer 32

reaction is at equilibrium, there is not shift

Question 33

what does it mean if q is less than K

Answer 33

reaction will shift to the products

Question 34

what does it mean if q>k

Answer 34

reaction will shift to the reactants

Question 35

what do we use when calculaing Kc when one equilibrium concentration is known

Answer 35

an ICE table

Question 36

what are the steps for calculating an ICE table

Answer 36

1. ) write down all known initial and equilibrium concentrations 2. ) calculate the change 3. ) use the coefficients of the reaction to calculate C for the remaining 4. ) calculate E

Question 37

steps for calculating eq. conc. from the initial concentrations

Answer 37

1. ) treat the change in the concentration as X 2. ) use the coefficients from the balanced equation for the coefficient of X 3. ) X is positive for for products and X is negative for reactants - use the quadratic formula to solve

Question 38

if Kc is small, how does that affect the large initial concentrations of the reaction

Answer 38

the reactant concentration will not change significantly

Question 39

how to check the validity of the approximation

Answer 39

approximate / initial conc. x 100 = <5%

Question 40

who discovered Le Chatelier's principle

Answer 40

Henri-louis le chatelier, the french chemist

Question 41

what is Le Chatlier's principle

Answer 41

1. ) system starts at equilib. 2. ) a change in the system cab be made by concentration, volume, pressure, temp, catalyst 3. ) system responds by shifting to the right (prod) or left(react) to restore equlibrium

Question 42

what does le Chatlier say about adding a substance even at equilibrium

Answer 42

add a substance, the reaction will shift to re-establish equilibrium by consuming part of the added substance ex: adding reactant = decrase the amounts of other reactant = shift towards the product

Question 43

why does adding a reactant increase the rate of the forward reaction

Answer 43

bc when you add more reactant then Qc is getting smaller than K so then we shift to the products

Question 44

what happens when you remove a substance from the reaction

Answer 44

move in the direction that forms more of that substance ex: removing a reactant will shift to replace it and it will increase the reactants - decreases the rate of the reaction

Question 45

where is hemoglobin found

Answer 45

protein that is found in red blood cells that reacts with O2

Question 46

what is the purpose of hemoglobin

Answer 46

enhances the amount of O2 that can be carried through the bloodstream

Question 47

what happens when a system's volume decreases

Answer 47

pressure increases, system will shift towards the fewer moles of gas

Question 48

what happens when a systems volume increases

Answer 48

pressure goes down, shift toward more moles of gas

Question 49

what effect does pressure and volume have on equlibrium

Answer 49

they have no effect bc changing the size of the container has no effect

Question 50

what is boyle's law

Answer 50

decreasing the containter volume = increasing the total pressure

Question 51

what is dalton's law of partial pressures

Answer 51

total pressures increase = partial pressures of all gases increase

Question 52

decreasing the container volume does what

Answer 52

- increase concentration of all gases | - same # of moles but different number of liters = different molarity

Question 53

what does adding a gas reactant do

Answer 53

increase the partial pressure bc equil. will shift to the right

Question 54

what will an inert/ unreactive gas do to the equilibrium

Answer 54

no effect

Question 55

what happens in an endothermic reaction

Answer 55

- heat is absorbed - heat is used to convert reactants into products - heat is a reactant

Question 56

what does an endothermic reaction do to K

Answer 56

increasing the temp causes the equi. to shift to the right (products) so K increases

Question 57

what happens in an exothermic reaction

Answer 57

- heat is released | - heat is treated as a product

Question 58

what happens to K in an exothermic reaction

Answer 58

equi. shifts to the left(reactants) b bc K decreases

Question 59

what happens to the equilibrium from heat being added

Answer 59

shift away from the added heat

Question 60

does a catalyst affec the position of equilibrium

Answer 60

no

Question 61

endothermic; increase temp

Answer 61

shift right, k increases

Question 62

endothermic; decrease temp

Answer 62

shift left, k decreases

Question 63

exothermic; increase temp

Answer 63

left, k decreases

Question 64

exothermic; decrease temp

Answer 64

right, k increases

Question 65

more moles of gas on right; increase volume

Answer 65

shift to the right, no effect on K

Question 66

more moles of gas o right; decrease volume

Answer 66

shift to the left

Question 67

more moles of gas on the left; increase volume

Answer 67

shift left

Question 68

more moles of gas on the left; decrease volume

Answer 68

shift right