Equilibrium State of balance. Condition in which opposing forces exactly balance or equal each...
-
Upload
esmond-brown -
Category
Documents
-
view
214 -
download
0
Transcript of Equilibrium State of balance. Condition in which opposing forces exactly balance or equal each...
![Page 1: Equilibrium State of balance. Condition in which opposing forces exactly balance or equal each other. Need a 2-way or reversible situation. Need a closed.](https://reader035.fdocuments.in/reader035/viewer/2022062519/5697bfba1a28abf838ca066a/html5/thumbnails/1.jpg)
![Page 2: Equilibrium State of balance. Condition in which opposing forces exactly balance or equal each other. Need a 2-way or reversible situation. Need a closed.](https://reader035.fdocuments.in/reader035/viewer/2022062519/5697bfba1a28abf838ca066a/html5/thumbnails/2.jpg)
Equilibrium
• State of balance.
• Condition in which opposing forces exactly balance or equal each other.
• Need a 2-way or reversible situation.
• Need a closed system.
![Page 3: Equilibrium State of balance. Condition in which opposing forces exactly balance or equal each other. Need a 2-way or reversible situation. Need a closed.](https://reader035.fdocuments.in/reader035/viewer/2022062519/5697bfba1a28abf838ca066a/html5/thumbnails/3.jpg)
Dynamic Equilibrium
• Macroscopic level – looks like nothing is happening.
• Microscopic level – lots going on.
![Page 4: Equilibrium State of balance. Condition in which opposing forces exactly balance or equal each other. Need a 2-way or reversible situation. Need a closed.](https://reader035.fdocuments.in/reader035/viewer/2022062519/5697bfba1a28abf838ca066a/html5/thumbnails/4.jpg)
Equilibrium
• Rate of forward process = rate of reverse process.
• Hallmark: Looks like nothing is happening. Variables describing system are constant.
![Page 5: Equilibrium State of balance. Condition in which opposing forces exactly balance or equal each other. Need a 2-way or reversible situation. Need a closed.](https://reader035.fdocuments.in/reader035/viewer/2022062519/5697bfba1a28abf838ca066a/html5/thumbnails/5.jpg)
3 Kinds of Equilibria
• Phase equilibrium – physical
• Solution equilibrium – physical
• Chemical equilibrium - chemical
![Page 6: Equilibrium State of balance. Condition in which opposing forces exactly balance or equal each other. Need a 2-way or reversible situation. Need a closed.](https://reader035.fdocuments.in/reader035/viewer/2022062519/5697bfba1a28abf838ca066a/html5/thumbnails/6.jpg)
Phase Equilibrium
• Phase changes are reversible processesPhase changes are reversible processes.
• H2O(l) H2O(g)
• H2O(l) H2O(s)
• Same substance on both sides. Phase is different.
![Page 7: Equilibrium State of balance. Condition in which opposing forces exactly balance or equal each other. Need a 2-way or reversible situation. Need a closed.](https://reader035.fdocuments.in/reader035/viewer/2022062519/5697bfba1a28abf838ca066a/html5/thumbnails/7.jpg)
Examples - Phase Equilibrium
• Water & water vapor in a sealed water bottle.
• Perfume in a partially full, sealed flask.• Ice cubes & water in an insulated
container.
• Dry ice & CO2(g) in a closed aquarium.
![Page 8: Equilibrium State of balance. Condition in which opposing forces exactly balance or equal each other. Need a 2-way or reversible situation. Need a closed.](https://reader035.fdocuments.in/reader035/viewer/2022062519/5697bfba1a28abf838ca066a/html5/thumbnails/8.jpg)
Solution Equilibrium: Solids
• Saturated solution = dynamic equilibrium.
• Dissolving & Solidification occur at equal rates.
![Page 9: Equilibrium State of balance. Condition in which opposing forces exactly balance or equal each other. Need a 2-way or reversible situation. Need a closed.](https://reader035.fdocuments.in/reader035/viewer/2022062519/5697bfba1a28abf838ca066a/html5/thumbnails/9.jpg)
Solid in Liquid
• NaCl(s) NaCl(aq)
• Favored a little bit by higher temperature.
![Page 10: Equilibrium State of balance. Condition in which opposing forces exactly balance or equal each other. Need a 2-way or reversible situation. Need a closed.](https://reader035.fdocuments.in/reader035/viewer/2022062519/5697bfba1a28abf838ca066a/html5/thumbnails/10.jpg)
Solution Equilibrium: Gases
CO2 in water unopened.
CO2(g) CO2(aq)
Favored by high pressure & low temperature.
![Page 11: Equilibrium State of balance. Condition in which opposing forces exactly balance or equal each other. Need a 2-way or reversible situation. Need a closed.](https://reader035.fdocuments.in/reader035/viewer/2022062519/5697bfba1a28abf838ca066a/html5/thumbnails/11.jpg)
Reversible ReactionsReversible Reactions
• N2(g) + 3H2(g) 2NH3(g)
• ForwardForward: N2 & H2 consumed. NH3 produced.
• 2NH3(g) N2(g) + 3H2(g)
• ReverseReverse: NH3 consumed. N2 & H2 produced.
![Page 12: Equilibrium State of balance. Condition in which opposing forces exactly balance or equal each other. Need a 2-way or reversible situation. Need a closed.](https://reader035.fdocuments.in/reader035/viewer/2022062519/5697bfba1a28abf838ca066a/html5/thumbnails/12.jpg)
Reversible Reactions, 1 Equation
• N2(g) + 3H2(g) 2NH3(g)
• Forward rxn, reactants are on left. Read left to right.
• Reverse rxn, reactants are on right. Read in reverse – right to left.
• Rxns run in both directions all the time.
![Page 13: Equilibrium State of balance. Condition in which opposing forces exactly balance or equal each other. Need a 2-way or reversible situation. Need a closed.](https://reader035.fdocuments.in/reader035/viewer/2022062519/5697bfba1a28abf838ca066a/html5/thumbnails/13.jpg)
Time
Conce
ntr
ati
on
NH3
H2
N2
N2(g) + 3H2(g) 2NH3(g)
Why is this point Why is this point significant?significant?
![Page 14: Equilibrium State of balance. Condition in which opposing forces exactly balance or equal each other. Need a 2-way or reversible situation. Need a closed.](https://reader035.fdocuments.in/reader035/viewer/2022062519/5697bfba1a28abf838ca066a/html5/thumbnails/14.jpg)
Reaction Rate
• Depends on concentration of reactants.
• As concentration of reactants decreases, rate decreases.
• As concentration of NH3 increases, rate of reverse rxn increases.
![Page 15: Equilibrium State of balance. Condition in which opposing forces exactly balance or equal each other. Need a 2-way or reversible situation. Need a closed.](https://reader035.fdocuments.in/reader035/viewer/2022062519/5697bfba1a28abf838ca066a/html5/thumbnails/15.jpg)
Chemical Equilibrium
• State in which forward & reverse rxns balance each other.
• RateRateforwardforward rxnrxn = Rate = Ratereversereverse rxnrxn
• Does it say anything about the concentrations of reactants & products being equal? NO!NO!
![Page 16: Equilibrium State of balance. Condition in which opposing forces exactly balance or equal each other. Need a 2-way or reversible situation. Need a closed.](https://reader035.fdocuments.in/reader035/viewer/2022062519/5697bfba1a28abf838ca066a/html5/thumbnails/16.jpg)
Chemical Equilibrium
• Rateforward rxn = Ratereverse rxn
• At equilibrium, the concentrations of all species are constantconstant. They stop changing.
• They are hardly ever equal.
![Page 17: Equilibrium State of balance. Condition in which opposing forces exactly balance or equal each other. Need a 2-way or reversible situation. Need a closed.](https://reader035.fdocuments.in/reader035/viewer/2022062519/5697bfba1a28abf838ca066a/html5/thumbnails/17.jpg)
Reversible Reactions vs. Reactions that “Go to Completion”
• If your goal is to maximize product yield:
• Easier in a reaction that goes to completion.
• Use up all the reactants.
• Left with nothing but product.
• Reversible reactions are different.
• Look at Conc/time picture again.
![Page 18: Equilibrium State of balance. Condition in which opposing forces exactly balance or equal each other. Need a 2-way or reversible situation. Need a closed.](https://reader035.fdocuments.in/reader035/viewer/2022062519/5697bfba1a28abf838ca066a/html5/thumbnails/18.jpg)
Time
Conce
ntr
ati
on
NH3
H2
N2
N2(g) + 3H2(g) 2NH3(g)
OriginalEquilibrium Point
![Page 19: Equilibrium State of balance. Condition in which opposing forces exactly balance or equal each other. Need a 2-way or reversible situation. Need a closed.](https://reader035.fdocuments.in/reader035/viewer/2022062519/5697bfba1a28abf838ca066a/html5/thumbnails/19.jpg)
Reversible Reactions
• Once you reach equilibrium, you don’t produce any more product.
• This is bad news if the product is what you’re selling.
• How can you change the equilibrium concentrations? For example, how can you maximize product?
![Page 20: Equilibrium State of balance. Condition in which opposing forces exactly balance or equal each other. Need a 2-way or reversible situation. Need a closed.](https://reader035.fdocuments.in/reader035/viewer/2022062519/5697bfba1a28abf838ca066a/html5/thumbnails/20.jpg)
How can you get from here
![Page 21: Equilibrium State of balance. Condition in which opposing forces exactly balance or equal each other. Need a 2-way or reversible situation. Need a closed.](https://reader035.fdocuments.in/reader035/viewer/2022062519/5697bfba1a28abf838ca066a/html5/thumbnails/21.jpg)
Lots of product as fast as possible.
New equilibrium point
To here?
![Page 22: Equilibrium State of balance. Condition in which opposing forces exactly balance or equal each other. Need a 2-way or reversible situation. Need a closed.](https://reader035.fdocuments.in/reader035/viewer/2022062519/5697bfba1a28abf838ca066a/html5/thumbnails/22.jpg)
Affecting Equilibrium
• Equilibrium can be changed or affected by any factor that affects the forward and reverse reactions differently.
![Page 23: Equilibrium State of balance. Condition in which opposing forces exactly balance or equal each other. Need a 2-way or reversible situation. Need a closed.](https://reader035.fdocuments.in/reader035/viewer/2022062519/5697bfba1a28abf838ca066a/html5/thumbnails/23.jpg)
What factors affect rate of rxn?
• Concentration/Pressure
• Temperature
• Presence of a catalyst
![Page 24: Equilibrium State of balance. Condition in which opposing forces exactly balance or equal each other. Need a 2-way or reversible situation. Need a closed.](https://reader035.fdocuments.in/reader035/viewer/2022062519/5697bfba1a28abf838ca066a/html5/thumbnails/24.jpg)
Catalyst
• Has the same effect on the forward & reverse reactions.
• Equilibrium is reached more quickly, but the “equilibrium point” is not shifted.
• The equilibrium concentrations are the same with or without a catalyst.
![Page 25: Equilibrium State of balance. Condition in which opposing forces exactly balance or equal each other. Need a 2-way or reversible situation. Need a closed.](https://reader035.fdocuments.in/reader035/viewer/2022062519/5697bfba1a28abf838ca066a/html5/thumbnails/25.jpg)
Concentration, Pressure, Temperature
• Changes in concentration, pressure, temperature affect forward & reverse rxns differently.
• Composition of equilibrium mixture will shift to accommodate these changes.
![Page 26: Equilibrium State of balance. Condition in which opposing forces exactly balance or equal each other. Need a 2-way or reversible situation. Need a closed.](https://reader035.fdocuments.in/reader035/viewer/2022062519/5697bfba1a28abf838ca066a/html5/thumbnails/26.jpg)
LeChatelier’s Principle
• “If a system at equilibrium is subjected to a stress, the system will act to reduce the stress.”
• A stress is a change in concentration, pressure, or temperature.
• System tries to undo stress.
![Page 27: Equilibrium State of balance. Condition in which opposing forces exactly balance or equal each other. Need a 2-way or reversible situation. Need a closed.](https://reader035.fdocuments.in/reader035/viewer/2022062519/5697bfba1a28abf838ca066a/html5/thumbnails/27.jpg)
N2(g) + 3H2(g) 2NH3(g)
N2
H2
NH3
Stress: Increased [N2]
Original Equilibrium
New Equilibrium
![Page 28: Equilibrium State of balance. Condition in which opposing forces exactly balance or equal each other. Need a 2-way or reversible situation. Need a closed.](https://reader035.fdocuments.in/reader035/viewer/2022062519/5697bfba1a28abf838ca066a/html5/thumbnails/28.jpg)
System
• Only 2 possible actionsOnly 2 possible actions
• Shift to the rightShift to the right & form more product. The forward rxn speeds upforward rxn speeds up more than the reverse rxn.
• Shift to the leftShift to the left & form more reactant. The reverse reaction speeds upreverse reaction speeds up more than the forward rxn.
![Page 29: Equilibrium State of balance. Condition in which opposing forces exactly balance or equal each other. Need a 2-way or reversible situation. Need a closed.](https://reader035.fdocuments.in/reader035/viewer/2022062519/5697bfba1a28abf838ca066a/html5/thumbnails/29.jpg)
A + B C + D, at equil.
• If I increase the concentration of A, how will the system react?
• How does the new equilibrium mixture compare to the original equilibrium mixture?
• Use logic. If you increase [A], the system wants to decrease [A]. It has to use A up, so it speeds up the forward reaction.
![Page 30: Equilibrium State of balance. Condition in which opposing forces exactly balance or equal each other. Need a 2-way or reversible situation. Need a closed.](https://reader035.fdocuments.in/reader035/viewer/2022062519/5697bfba1a28abf838ca066a/html5/thumbnails/30.jpg)
A + B C + D
Stress Equil. Shift
[A] [B] [C] [D]
[A] Right ______ DEC INC INC
[D] Left INC INC DEC ______
[C] Right DEC DEC ______ INC
[B] Left INC ______ DEC DEC
![Page 31: Equilibrium State of balance. Condition in which opposing forces exactly balance or equal each other. Need a 2-way or reversible situation. Need a closed.](https://reader035.fdocuments.in/reader035/viewer/2022062519/5697bfba1a28abf838ca066a/html5/thumbnails/31.jpg)
Changes in Temp• Exothermic rxn:
• A + B C + D + heat
• If you increase the temperature, the system shifts to consumeconsume heat. So here, it shifts to the left.
• Endothermic rxn:
• A + B + heat C + D
• If you increase the temperature, the system shifts to consume heat. So here, it shifts to the right.
![Page 32: Equilibrium State of balance. Condition in which opposing forces exactly balance or equal each other. Need a 2-way or reversible situation. Need a closed.](https://reader035.fdocuments.in/reader035/viewer/2022062519/5697bfba1a28abf838ca066a/html5/thumbnails/32.jpg)
Changes in Pressure
• N2(g) + 3H2(g) 2NH3(g)
• If you increase pressure, the system shifts to the side with fewer moles of gas. Here, the right hand side has only 2 moles of gas while the LHS has 4. Increasing pressure will cause a shift to the right.
• If you decrease pressure, the system shifts to the side with more moles of gas.
![Page 33: Equilibrium State of balance. Condition in which opposing forces exactly balance or equal each other. Need a 2-way or reversible situation. Need a closed.](https://reader035.fdocuments.in/reader035/viewer/2022062519/5697bfba1a28abf838ca066a/html5/thumbnails/33.jpg)
H2(g) + I2(g) 2HI(g)
• This system has 2 moles of gas on the LHS & 2 moles of gas on the RHS.
• Systems with equal moles of gas on each side cannotcannot respond to pressure changes.