Slide 1 : chemical
equilibrium!
Slide 2 : First, a metaphor: Two floors of a store are
connected by up and down escalators Floor 1 has 7 people,
floor 2 has 12 people. There are always 2 people
occupying each escalator
Slide 3 : Floor 2: 7 people Floor 1:
12 people
Slide 4 : Floor 2: 7 people Floor 1:
12 people 2 people
on the up
escalator 2 people
on down
escalator
Slide 5 : Floor 2: 7 people Floor 1:
12 people 2 people
on the up
escalator 2 people
on down
escalator Question 1: if there are always two people on
each escalator at any one moment, will the amount
of people on each floor ever change?
Slide 6 : Floor 2: 7 people Floor 1:
12 people 2 people
on the up
escalator 2 people
on down
escalator Question 2: if there are always two people on
each escalator at any one moment, will the specific people
occupying each floor ever change?
Slide 7 :
Slide 8 : The double arrow tells us that
this reaction can go in both directions:
Slide 9 : 1) Reactants react to become products, N2 + 3H2 2NH3 (‘forward’ reaction)
Slide 10 : 1) Reactants react to become products, while simultaneously, N2 + 3H2 2NH3 (‘forward’ reaction) 2) Products react to become reactants N2 + 3H2 2NH3 (‘reverse’ reaction)
Slide 11 : In a closed system,
where no reactants, products, or energy
can be added to or removed from the reaction,
a reversible reaction will reach equilibrium.
Slide 12 : At equilibrium, the rate of the forward reaction
becomes equal to the rate of the reverse reaction,
and so, like our escalator metaphor, the two sides,
reactants and products,
will have constant amounts,
even though the reactions continue to occur.
Slide 13 : However (like the metaphor),
the equilibrium amounts of
reactants and products
are usually not equal,
they just remain unchanged.
Slide 14 : N2 + 3H2 2NH3
Slide 15 : N2 + 3H2 2NH3
Slide 16 : N2 + 3H2 2NH3
Slide 17 : N2 + 3H2 2NH3
Slide 18 :
Slide 19 :
Slide 20 :
Slide 21 :
Slide 22 :
Slide 23 : reverse forward
Slide 24 : reverse forward
Slide 25 : reverse forward
Slide 26 : reverse forward
Slide 27 : reverse forward
Slide 28 :
Slide 29 :
Slide 30 : reverse forward
Slide 31 : reverse forward
Slide 32 : reverse forward
Slide 33 : reverse forward
Slide 34 : reverse forward
Slide 35 :
Slide 36 : etc!
the reactions go on continuously in both directions. reverse forward
Slide 37 : Changes in the concentrations
of the reactants and products
can be graphed;
the graph indicates when
equilibrium has been reached. concentration time
Slide 38 : For N2 + 3H2 2NH3,
suppose you begin with the following:
N2 = 1 M, H2 = 1 M, and NH3 = 0 M concentration time
Slide 39 : For N2 + 3H2 2NH3,
suppose you begin with the following:
N2 = 1 M, H2 = 1 M, and NH3 = 0 M concentration time
Slide 40 : For N2 + 3H2 2NH3,
suppose you begin with the following:
N2 = 1 M, H2 = 1 M, and NH3 = 0 M concentration time
Slide 41 : For N2 + 3H2 2NH3,
suppose you begin with the following:
N2 = 1 M, H2 = 1 M, and NH3 = 0 M concentration time
Slide 42 : For N2 + 3H2 2NH3,
suppose you begin with the following:
N2 = 1 M, H2 = 1 M, and NH3 = 0 M concentration time
Slide 43 : For N2 + 3H2 2NH3,
suppose you begin with the following:
N2 = 1 M, H2 = 1 M, and NH3 = 0 M concentration time
Slide 44 : For N2 + 3H2 2NH3,
suppose you begin with the following:
N2 = 1 M, H2 = 1 M, and NH3 = 0 M concentration time
Slide 45 : For N2 + 3H2 2NH3,
suppose you begin with the following:
N2 = 1 M, H2 = 1 M, and NH3 = 0 M concentration time
Slide 46 : For N2 + 3H2 2NH3,
suppose you begin with the following:
N2 = 1 M, H2 = 1 M, and NH3 = 0 M concentration time
Slide 47 : For N2 + 3H2 2NH3,
suppose you begin with the following:
N2 = 1 M, H2 = 1 M, and NH3 = 0 M concentration time
Slide 48 : For N2 + 3H2 2NH3,
suppose you begin with the following:
N2 = 1 M, H2 = 1 M, and NH3 = 0 M concentration time
Slide 49 : For N2 + 3H2 2NH3,
suppose you begin with the following:
N2 = 1 M, H2 = 1 M, and NH3 = 0 M concentration time
Slide 50 : For N2 + 3H2 2NH3,
suppose you begin with the following:
N2 = 1 M, H2 = 1 M, and NH3 = 0 M concentration time
Slide 51 : For N2 + 3H2 2NH3,
suppose you begin with the following:
N2 = 1 M, H2 = 1 M, and NH3 = 0 M concentration time
Slide 52 : For N2 + 3H2 2NH3,
suppose you begin with the following:
N2 = 1 M, H2 = 1 M, and NH3 = 0 M concentration time
Slide 53 : For N2 + 3H2 2NH3,
suppose you begin with the following:
N2 = 1 M, H2 = 1 M, and NH3 = 0 M concentration time
Slide 54 : For N2 + 3H2 2NH3,
suppose you begin with the following:
N2 = 1 M, H2 = 1 M, and NH3 = 0 M concentration time
Slide 55 : For N2 + 3H2 2NH3,
suppose you begin with the following:
N2 = 1 M, H2 = 1 M, and NH3 = 0 M concentration time [N2] [H2] [NH3]
Slide 56 : For N2 + 3H2 2NH3,
suppose you begin with the following:
N2 = 1 M, H2 = 1 M, and NH3 = 0 M concentration time Question 3: at what point
has equilibrium been established? [N2] [H2] [NH3]
Slide 57 : For N2 + 3H2 2NH3,
suppose you begin with the following:
N2 = 1 M, H2 = 1 M, and NH3 = 0 M concentration time Question 4: what does the graph tell you about the
concentration of each species once equilibrium is established? [N2] [H2] [NH3]
Slide 58 : For N2 + 3H2 2NH3,
suppose you begin with the following:
N2 = 1 M, H2 = 1 M, and NH3 = 0 M concentration time Question 5: what might a rate vs time graph
look like for the above reaction? [N2] [H2] [NH3]
Slide 59 : rate time Question 5: what might a rate vs time graph
look like for the above reaction? For and still beginning with N2 = 1 M, H2 = 1 M, and NH3 = 0 M
Slide 60 : For and still beginning with rate time N2 = 1 M, H2 = 1 M, and NH3 = 0 M
Slide 61 : For and still beginning with rate time N2 = 1 M, H2 = 1 M, and NH3 = 0 M Question 6: at what point
has equilibrium been established? forward reverse
Slide 62 : rate time Question 7: describe how the two graphs are related. concentration time N2 H2 NH3 forward reverse
Slide 63 : Question 8: do either of the two graphs
indicate if Keq >1 or Keq <1? concentration time N2 H2 NH3 forward reverse