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Response of Equilibria to Change

Posted: Sun Jan 12, 2020 9:10 pm
by 205389184
Could somebody explain the quick way to determine a response of equilibria to change? Dr. Lavelle mentioned it in lecture but I hadn't heard of it prior to when he talked about it so I'm still a little confused.

Re: Response of Equilibria to Change

Posted: Sun Jan 12, 2020 9:11 pm
by MingdaH 3B
The rule of thumb is that the equilibrium will respond in a way that counteracts the change. However, this doesn't give you an accurate representation, so the best way to do so is to recalculate using equations to determine equilibrium.

Re: Response of Equilibria to Change

Posted: Sun Jan 12, 2020 9:14 pm
by Gerald Bernal1I
With any change the equilibrium will shift a certain way. A general rule is if there is more of reactant, the equilibrium will shift to the right (product) since it has more reactants to form product, and the same goes for an increase of product concentration: it will shift left to create the reactants. For pressure it depends if the volume is being changed or if an inert gas is being added. Change in volume will affect concentration which will follow the rule mentioned above and an inert gas will not affect the system.

Re: Response of Equilibria to Change

Posted: Sun Jan 12, 2020 9:16 pm
by Sue Bin Park 2I
he was talking mainly about if you are trying to figure out how an equilibrium reacts to a change in pressure.

example equation: A(g) + 2B(g) <-> 2C(g)
if pressure is increased: the equilibrium will shift to produce more of the side that has less overall moles of gas. in our example, it's the right side. this is bc increasing the pressure will incline the system to decrease it in response (le chatelier) and the way to do so is decrease the overall particles of gas that are exerting this "pressure"
if pressure is decreased: the eq will shift to produce the side that has more moles of gas. our left side of the example.

he said this logic isn't quite the whole picture but theres the reasoning we learn in hs chem anyway lol

Re: Response of Equilibria to Change

Posted: Sun Jan 12, 2020 9:18 pm
by Sjeffrey_1C
He basically said that if volume decreases and there are more moles of gas on left, then the reaction shifts left, or if volume decreases and there are more moles of gas on the right, then the reaction shifts left. But this logic is incorrect.

Re: Response of Equilibria to Change

Posted: Sun Jan 12, 2020 9:22 pm
by Juliet Stephenson 4E
MingdaH 3B wrote:The rule of thumb is that the equilibrium will respond in a way that counteracts the change. However, this doesn't give you an accurate representation, so the best way to do so is to recalculate using equations to determine equilibrium.


Can you specify which equations we would use to recalculate? Would we just use the pV=nRT

Re: Response of Equilibria to Change

Posted: Sun Jan 12, 2020 9:29 pm
by 505306205
If stress is put on a system, then the reaction shifts in the direction that minimizes that stress.