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Offline kauzs-17

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Precipitation Reaction
« on: November 19, 2013, 04:29:55 AM »
Hello,

I'm given Na2CO3 (aq) + AgNO3 (aq)
Dissolved in .400L of water
I get Na+ + Na+ + CO32- + Ag+ + NO3-

But I can't seem to form a precipitate with this. I feel as though I should because another problem gives the g amount of the reactants and asks which is limiting.
« Last Edit: November 19, 2013, 07:35:45 AM by kauzs-17 »

Offline Arkcon

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Re: Precipitation Reaction
« Reply #1 on: November 19, 2013, 04:39:10 AM »
You will have to look up the general solubility rules.  There is most definitely a precipitate.
Hey, I'm not judging.  I just like to shoot straight.  I'm a man of science.

Offline kauzs-17

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Re: Precipitation Reaction
« Reply #2 on: November 19, 2013, 06:23:54 AM »
Solubility Rules given to me from my teacher (Straight from Powerpoint).

Some compounds always dissociate (break up) in solution.
•   Any anion with an alkali metal (first column) or NH4+
•   Any metal with: NO3-, HCO3-, and ClO3-.
Some compounds never dissociate:
•   Halides with Ag+, Hg2+, and Pb2+
•   Sulfates with Ag+, Cd2+, Sr2+, or Pb2+
•   Metals with CO32-, PO43-, CrO42-, or S2-, unless they are akali metals.
•   Metals with OH-, unless they are alkali metals.
Na+ is an alkali metal so it's out.
That leaves CO32-, NO3- and Ag+.
NO3- dissociates with all metals, plus AgNO3 is a reactant. That's out.
And there is only one Ag+ so there's no other option.

Is there something I'm missing?

Offline AWK

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Re: Precipitation Reaction
« Reply #3 on: November 19, 2013, 07:19:05 AM »
Quote
Is there something I'm missing?
I'm given Na2CO3 (aq) + AgNO3 (aq)
AWK

Offline kauzs-17

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Re: Precipitation Reaction
« Reply #4 on: November 19, 2013, 07:30:40 AM »
Quote
Is there something I'm missing?
I'm given Na2CO3 (aq) + AgNO3 (aq)
Yes... I'm sorry I'm just not wrapping my head around this..

Offline DrCMS

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Re: Precipitation Reaction
« Reply #5 on: November 19, 2013, 07:32:40 AM »
Na+ is an alkali metal so it's out.
That leaves CO32-, NO3- and Ag+.
NO3- dissociates with all metals, plus AgNO3 is a reactant. That's out.
And there is only one Ag+ so there's no other option.

Is there something I'm missing?

Look again you have 4 ions and you've only ruled out only 2 of them

Offline kauzs-17

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Re: Precipitation Reaction
« Reply #6 on: November 19, 2013, 07:35:09 AM »
Alright, so to clarify, I get
Na+ + Na+ + CO32-- + Ag+ + NO3-?
Right?

Offline kauzs-17

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Re: Precipitation Reaction
« Reply #7 on: November 19, 2013, 07:41:13 AM »
Wait...
You can't form a precipitate with an overall - charge, can you?
Such as AgCO3-?

Offline Borek

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Re: Precipitation Reaction
« Reply #8 on: November 19, 2013, 08:15:12 AM »
They don't have have to react 1:1.

Do you know what is the formula of silver carbonate? Were you perhaps taught how to write formula of such compound? You already seem to know that salt molecule should be neutral - and the silver carbonate is made of Ag+ and CO32- - how can you combine them to produce a neutral molecule?
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Offline kauzs-17

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Re: Precipitation Reaction
« Reply #9 on: November 19, 2013, 09:25:45 AM »
Ag2CO3.
Since I only have a +1 charge and -2 charge, could it be Ag(CO3).50? Is that even possible?

I know when I did a stoichiometry problem for the empirical formula of Methane I got C.25H1 which would be CH4. Is this a similar deal?

Offline Borek

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Re: Precipitation Reaction
« Reply #10 on: November 19, 2013, 09:51:30 AM »
Ag2CO3.

Correct.

Quote
Since I only have a +1 charge and -2 charge, could it be Ag(CO3).50? Is that even possible?

No, it is not possible and it is not necessary. You already wrote correct formula of the salt above. As I told you earlier, sodium carbonate and silver nitrate don't react 1:1. See for yourself - try to balance this reaction equation:

Na2CO3 + AgNO3 :rarrow: Ag2CO3 + NaNO3

It is obvious that you have some misconception about how these things work, I just can't pinpoint it yet.
ChemBuddy chemical calculators - stoichiometry, pH, concentration, buffer preparation, titrations.info

Offline Vidya

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Re: Precipitation Reaction
« Reply #11 on: November 19, 2013, 10:20:35 AM »
Formulas are not decided by the amount of the ions present in the solution.The compounds combine in a fixed ratio.So here 2 moles Ag+ will combine with 1 mole of CO32-
so the precipitates are of
2Ag+ + CO32-----> Ag2CO3(s)
only IA group and NH4+ carbonates are soluble and rest all are insoluble.

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