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Topic: 2 questions about equilibrium  (Read 10356 times)

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777888

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2 questions about equilibrium
« on: January 06, 2005, 10:33:52 AM »
1.Describe and explain a situation in which a soft drink is in a non-equilibrium state.
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I don't really know this question...would a soft dirnk bottle that is opened be a system not at equilibrium...?! When a soft drink bottle is opened, would CO2(g)->CO2(aq) be favoured or CO2(aq)->CO2(g) be favoured? Would there be more gas produced in open bottle or closed bottle?
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2.A series of experiments with a non-aqueous solvent determined that the products are highly favoured in each of the following acid-base equilibria.
(C6H5)3C- + C4H4NH <-> (C6H5)3CH+ C4H4N-
HC2H3O2 + HS- <-> H2S + C2H3O2-
O2- + (C6H5)3CH <-> (C6H5)3C- + OH-
C4H4N- + H2S <-> C4H4NH + HS-
Arrange the acids in the 4 chem. rxns in order of decreasing acid strength.
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I am completely lost...I identified the B-L acids and conjugate pairs...but I have no idea how to which one is stronger!

I have to understand these before the test...I need *delete me* Please teach me! Thank you so much! :)
« Last Edit: January 06, 2005, 10:35:58 AM by 777888 »

Offline Donaldson Tan

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Re:2 questions about equilibrium
« Reply #1 on: January 06, 2005, 10:58:12 AM »
1. solubility of CO2 is directly proportional to the pressure acting on it

2. among these acids, which one do u think is most likely to dissociate to produce H+ ?
"Say you're in a [chemical] plant and there's a snake on the floor. What are you going to do? Call a consultant? Get a meeting together to talk about which color is the snake? Employees should do one thing: walk over there and you step on the friggin� snake." - Jean-Pierre Garnier, CEO of Glaxosmithkline, June 2006

Demotivator

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Re:2 questions about equilibrium
« Reply #2 on: January 06, 2005, 11:18:37 AM »
H2CO3 <-> H2O + CO2(g)
In a closed bottle it is at equilibrium since the CO2 gas cannot escape.
In an open bottle, the gas escapes, driving the reaction to the right to a non equilibrium.

2) First, for each rxn determine which acid in the pair is more acidic
 C4H4NH > (C6H5)3CH because it is donating H+ to form product on right.
 HC2H3O2 > H2S
etc
etc

Then arrange them all in one series

777888

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Re:2 questions about equilibrium
« Reply #3 on: January 06, 2005, 12:47:05 PM »
Thank you geodome and Demotivator.

For Q2, how can I know which acid is stronger in the 4 chemical reactions?
Also, do I have to use the fact that "products are highly favoured"?
« Last Edit: January 06, 2005, 12:47:51 PM by 777888 »

Demotivator

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Re:2 questions about equilibrium
« Reply #4 on: January 06, 2005, 01:01:00 PM »
 There is one acid on each side of the equation. If the acid on the right is stronger, the reaction would go left and vice versa.
You are told the reactions all go to the right.
« Last Edit: January 06, 2005, 01:03:44 PM by Demotivator »

777888

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Re:2 questions about equilibrium
« Reply #5 on: January 06, 2005, 03:28:54 PM »
There is one acid on each side of the equation. If the acid on the right is stronger, the reaction would go left and vice versa.
You are told the reactions all go to the right.
Oh, I see...
But do I have to arrange all the acids between the 4 chemical reactions in decreasing order too? Or just within each chem. rxn? (maybe I misunderstood the question :P)
« Last Edit: January 06, 2005, 03:37:29 PM by 777888 »

Demotivator

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Re:2 questions about equilibrium
« Reply #6 on: January 06, 2005, 03:39:38 PM »
I already told you in a previous message:
"First, for each rxn determine which acid in the pair is more acidic"

"Then arrange them all in one series "

By using Logic.



777888

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Re:2 questions about equilibrium
« Reply #7 on: January 06, 2005, 03:53:52 PM »
(C6H5)3C- + C4H4NH <-> (C6H5)3CH+ C4H4N-
HC2H3O2 + HS- <-> H2S + C2H3O2-
O2- + (C6H5)3CH <-> (C6H5)3C- + OH-
C4H4N- + H2S <-> C4H4NH + HS-

C4H4NH > (C6H5)3CH

HC2H3O2 > H2S

(C6H5)3CH > OH-

H2S > C4H4NH

* > stronger
« Last Edit: January 06, 2005, 03:54:15 PM by 777888 »

Demotivator

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Re:2 questions about equilibrium
« Reply #8 on: January 06, 2005, 03:56:48 PM »
correct. Now put them all in one sequence.

777888

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Re:2 questions about equilibrium
« Reply #9 on: January 06, 2005, 04:50:09 PM »
correct. Now put them all in one sequence.
oh yeah...I get it now! Thank you! :D

Demotivator

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Re:2 questions about equilibrium
« Reply #10 on: January 06, 2005, 09:47:36 PM »
"I seeee!" said the blind man.  ;D

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