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Topic: Why add NH3 to CaCl2 in this experiment??  (Read 8898 times)

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Offline Archdevil155

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Re: Why add NH3 to CaCl2 in this experiment??
« Reply #15 on: May 10, 2013, 06:52:44 AM »
Yea I met with my former Chem teacher that I mentioned before and he explained it quite well..:) And now I get what you mean about NH3, thanks for all the help man.. He said that the way it's said in the Lab guide book (some dense NH3) it means that it doesn't react because it's too little compared to the CaCl2 and it's just there to adjust the pH and neutralize HPO42-, just as you said.. :) Thanks again and now I'm writing and completing the report :)

Offline Archdevil155

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Re: Why add NH3 to CaCl2 in this experiment??
« Reply #16 on: May 10, 2013, 09:11:13 AM »
Sorry to ask again on this topic, but can you type the dissociation equation of Na2HPO4 * 12H2O in water please??

It's in solid state in the form of small crystals-powder, if that's any help..

Offline Arkcon

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Re: Why add NH3 to CaCl2 in this experiment??
« Reply #17 on: May 10, 2013, 11:03:32 AM »
Sorry to ask again on this topic, but can you type the dissociation equation of Na2HPO4 * 12H2O in water please??

What ions do you expect to be able to get, given the formula?  Take a random stab, see what you get, we can help afterward.

Quote
It's in solid state in the form of small crystals-powder, if that's any help..

None of that has any bearing on this question.  I hope you can see that.  Note: the water of hydration likewise has no effect on this problem, I hope you can see that.
Hey, I'm not judging.  I just like to shoot straight.  I'm a man of science.

Offline Archdevil155

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Re: Why add NH3 to CaCl2 in this experiment??
« Reply #18 on: May 10, 2013, 11:26:19 AM »
Yea I thought so just making sure.. My problem wasn't about Na2HPO4 but the 12H2O. Whether they do something or not.. I didn't really think so but I wanted to know for sure. Na2HPO4  :rarrow: 2Na+ + HPO42-. So since the 12H2O don't participate in the chemical equation I'm covered.. :)

Offline Arkcon

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Re: Why add NH3 to CaCl2 in this experiment??
« Reply #19 on: May 10, 2013, 01:07:31 PM »
So what would happen to 12 molecules of H2O locked into the solid's crystal lattice when the solid dissolves in water?  Can you determine how many molecules of water there are in 1 ml?  That would help you understand.
Hey, I'm not judging.  I just like to shoot straight.  I'm a man of science.

Offline alejmam

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Re: Why add NH3 to CaCl2 in this experiment??
« Reply #20 on: May 10, 2013, 06:59:52 PM »
sorry to bother or spam the conversation but I'd like to ask you if you study in Patra because I'm in the exact place with this experiment as you are .

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