Le chateliers principle (1 Viewer)

[richz]

can sumone plz elaborate on the change in pressure, change in conc and change in temp

 

[jamesy_1988]

Is this in relation to yeilds from chemical reactions. If so give me a day and i'll give you all the info that i have

jamesy

 

[Slidey]

can sumone plz elaborate on the change in pressure, change in conc and change in temp

When stress is applied to system at equilibrium, the system will adjust to relieve the stress.

Basically if there is a change in concentration, temperature or pressure, the system will favour one direction of the equilibrium to compensate for the change.

EDIT: Do you want to know about it in relation to CO2 and H2O?

 

[tennille]

can sumone plz elaborate on the change in pressure, change in conc and change in temp

Le Chatelier's Principle: If a chemical reaction system at equilibrium is subjected to a change in conditions, the system will adjust itlsef to re-establish equilibrium in such a way as to counteract the imposed.

Change in pressure.

If you increase the pressure of the equilibrium, then the reaction will go in the direction where there is less pressure.

eg. N2O4 (g) <---> 2NO2 (g)
----- 1 mole--------- 2 mole

If the pressure of this system is increased, then the reaction will go to the left since there is less moles of gas on the left. Increasing the pressure of the whole system leads to a decrease in volume.

Change in conc.

Increasing the concentration NO2 by adding more NO2 will result in the reaction moving towards the left so there is a decrease in the amount of NO2. If there is a removal of NO2, the reaction will go to the right to make more NO2.

Change in temp.

eg. N2 (g) + 3H2 (g) <---> 2NH3 (g) (exothermic reaction)

Heat is released when the reaction goes from left to right. If you increase the temp., the reaction will go in the direction to counteract this increase in heat, therefore, from right to left. If the temp. is decreased, then the reaction will go from left to right to cause an increase in heat.

 

[xiao1985]

my definition of le chataleir's principle: when a change is done to a system at equilibrium, the equilibrium will counter act the change by partially undoes the change by moving to a new equilibrium hence minimising the stress on the system...

 

[tennille]

my definition of le chataleir's principle: when a change is done to a system at equilibrium, the equilibrium will counter act the change by partially undoes the change by moving to a new equilibrium hence minimising the stress on the system...

My teacher got the definition I posted from some book. It sounds really complicated though.

 

[Trev]

whats your email address? we were given this sheet on Le Chateliers principle and its really good, i can scan and send to u?!.....

 

[xiao1985]

whats your email address? we were given this sheet on Le Chateliers principle and its really good, i can scan and send to u?!.....

u can also attach here =D so everyone can see

 

[Mege]

that sheet on Le Chatliers principle sounds good can u send it to me?

 

[Dashin_Dan]

Our definition on Le Chateliers

Our definition is "If a system at equilibrium is disturbed, the system then adjusts itself to minimise the disturbance." There are 3 factors that can affect the equilibrium.

N2+3H2<->2NH3
CONCENTRATION
Reactants are added: Reaction will be pushed to the right.
Products are added: Reaction will be pushed to the left.
Reactants are removed: Reaction will be pushed to the left.
Products are removed: Reaction will be pushed to the right.

TEMPERATURE
For Exothermic:
Increasing Temp: Shifts left.
Decreasing Temp: Shifts right.
For Endothermic:
Increasing temp: Shifts right.
Decreasing Temp: Shifts left.

PRESSURE
Increasing Pressure(Decreasing volume): Shifts to the side with least moles.
Decreasing Pressure(Increasing volume): Shifts to the side with most moles.

N2+3H2<->2NH3
So the reactants have the most moles and products the least.

Hope this helps with Le Chateliers.

 

[daemonic666]

thanx i wasnt getting it in class but with that little blurb i understand.
(we wrote like five or six pages of notes!)

 

[richz]

le chatelier's principle

whats your email address? we were given this sheet on Le Chateliers principle and its really good, i can scan and send to u?!.....

thnx heres my email
mai1_m3@hotmail.com

 

[richz]

thnx dan and tennile helpful

 

[funking_you]

Normally i wouldn't do this, however i've attached a worksheet on Equilibrium Systems, it is very simple to understand.
Equilibrium is such an important concept, and once you get the hang of how to apply its concepts, you'll actually enjoy this part of the syllubus.

Read through, and work through the questions, and i guarantee you'll master this concept.

Any more questions, email me at
george@chemistrycoach.com.au

Cheers,
George


Get the worksheet here....

 

[richz]

ok guys if the equilibirum reaction was CO2 + H2O <--> H2CO3 if we increase the pressure would the reaction shift to the left??

 

[Slidey]

ok guys if the equilibirum reaction was CO2 + H2O <--> H2CO3 if we increase the pressure would the reaction shift to the left??

No. It would go to the right. There is less pressure there, which is where it wants to go.

You've increased pressure, so it wants to decrease pressure. It can do this by going forwards because there's only 1 mole on the right compared to 2 on the left.

Oh, and since pressure is proportional to temperature, would increasing the temperature also cause the equilibrium to go to the right, in this case?

 

[funking_you]

For the hsc, i don't think that you should mentioning the fact that "pressure is related to temperature"

The reaction in question is exothermic, and as such the reaction increasing the temperature would shift the equilibrium to the left (favouring the backward reaction).

If you really want to understand these concepts, download the worksheet on Chemical Equilibrium in my post on page one of this worksheet.

Cheers
George

 

[jisu]

where are the answers to those worksheets lol

 

[jisu]

also that document doesnt seem to factor in situations where Le Chatelier's principle doesn't apply, like when adding inert gas, or if a solid or liquid is present (that hasn't been dissolved).

aren't we supposed to know that as well?

 

[Casmira]

ok guys if the equilibirum reaction was CO2 + H2O <--> H2CO3 if we increase the pressure would the reaction shift to the left??

Nope to the right, ill explain how it works

the increase in pressure, so lechateliers principle is to counter-act that change, so in order for it to decrease the pressure, it needs to favour the side with less molecules