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777888

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2 questions
« on: November 13, 2004, 10:39:45 PM »
1a)Describe an experimental design(briefly) you could use to determine the solubility of Ca(OH)2 in water at 60oC
-I don't know how to do this question.

2)Why in electrochemisty, when we see H+ and OH- in a chemical reaction, we always (e.g. when balancing redox equations) combine them to form H2O?

Thanks for helping!

777888

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Re:2 questions
« Reply #1 on: November 15, 2004, 08:29:08 PM »
Also, I have some questions about "Chemical Systems in Equilibrium":

3)I don't get what is the diference between Dynamic Equilibrium and Solubility Equilibrium.

4)Why does stirring help to dissolve a solute?

Thank you!
« Last Edit: November 16, 2004, 04:29:47 PM by 777888 »

Offline Mitch

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Re:2 questions
« Reply #2 on: November 15, 2004, 09:01:07 PM »
4) Helps disperse the solute to other parts of the solution that doesn't have it in it. It's basically helping the entropy along.
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777888

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Re:2 questions
« Reply #3 on: November 16, 2004, 08:56:56 PM »
Why in electrochemisty, when we see H+ and OH- in a chemical reaction, we always (e.g. when balancing redox equations) combine them to form H2O?

Anyone know this?

Thanks

Offline Mitch

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Re:2 questions
« Reply #4 on: November 16, 2004, 09:19:57 PM »
Just part of the rules, I'm not sure if it has a chemical significance.
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Offline Donaldson Tan

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Re:2 questions
« Reply #5 on: November 17, 2004, 09:21:51 AM »
redox reactions that involves aqueous medium would use H+ and OH- to balance the charges. These ions are always present with water, why not use them to aid the electron transfer process?

dynamic equilibrium is achieved in a chemical system whereby the forward reaction rate equals the backward reaction rate, such that the composition of the system remains unchanged [steady].

solubility equilibrium refers to a specific type of dynamic of equilibrium whereby a substance dissolves in a solvent, eg. water.

figuring out solubility of calcium hydroxide at 60oC
1. dissolve excess calcium hydroxide at 60oC
2. filter the undissolved calcium hydroxide away.
3. heat the solution to 80degrees
4. titrate with appropriate indicator.

(3) is used because solubility increases with temperature. it helps to prevent re-precipitation of calcium hydroxide
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777888

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Re:2 questions
« Reply #6 on: November 18, 2004, 08:32:36 PM »
Thanks for your help :)

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