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#Post#: 1376--------------------------------------------------
Re: Problem of the week-19/11/12
DIR By: Shiva
Date: December 3, 2012, 7:35 am
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Many thanks for clarifying Mich :-)
Shiva
#Post#: 1377--------------------------------------------------
Re: Problem of the week-19/11/12
DIR By: Chemist@
Date: December 3, 2012, 8:45 am
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The biggest problem now is the dry reaction. I thought that Y is
O2 as KClO3 could be catalytic decomposed where one of the
unknown substances is the catalyst, but then the mass of Y
wouldn't help. I will need some time to think about it. To sum
up, I know that I got Na+, CO32- an unknown cation and an
unknown anion (NaCl not mentioned here). Therefore, the two
other compounds should be made: one from Na and the anion and
the other from CO32- and the cation.
#Post#: 1378--------------------------------------------------
Re: Problem of the week-19/11/12
DIR By: Michel
Date: December 3, 2012, 11:13 am
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--- Quote from: Chemist@ link ---
>
> Therefore, the two other compounds should be made: one from Na
and the anion and the other from CO32- and the cation.
>
--- End Quote ---
correct, more progress...
--- Quote from: Michel link ---
>
> When 5.00g of the mix is dissolved in 20 ml water, the
solution is alkaline, and the molar concentration of Na+ is
3.42M. 2.00g of a white suspension of undissolved particles was
also obtained.
>
--- End Quote ---
what do you infer from this?
#Post#: 1386--------------------------------------------------
Re: Problem of the week-19/11/12
DIR By: Chemist@
Date: December 3, 2012, 12:06 pm
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So, one of the compounds is CdCO3 and its mass share in the
mixture is 40%. I determined by calculation that the other
compound is Na2S or Na2O2 whose mass share is 40%, but I can't
think of a reaction that either of these could react with KClO3.
Isn't it the decomposition of KClO3 to produce O2?
#Post#: 1388--------------------------------------------------
Re: Problem of the week-19/11/12
DIR By: Shiva
Date: December 3, 2012, 12:13 pm
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Sodium sulfide is a reducing agent and it will react with
Potassium chlorate violently. Carbonates are alkaline in nature
so you need not to think of other alkali. But, why we need
Sodium chloride there, it still puzzles me.
Shiva
#Post#: 1389--------------------------------------------------
Re: Problem of the week-19/11/12
DIR By: Michel
Date: December 3, 2012, 12:24 pm
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Well, Chemist@...you've done a great job.
Either Na2S or Na2O2
Think of any of the two compounds that will react [in the
presence of decomposing KClO3] with other components of the
mixture
There's one reaction that gives Y.
#Post#: 1390--------------------------------------------------
Re: Problem of the week-19/11/12
DIR By: Michel
Date: December 3, 2012, 12:29 pm
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Shiva,
what are the products of Na2S + KClO3
#Post#: 1391--------------------------------------------------
Re: Problem of the week-19/11/12
DIR By: Chemist@
Date: December 3, 2012, 1:03 pm
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That reaction is:
3Na2S+4KClO3→4KCl+3Na2SO4, but there is no gas. When I
used the mass of Y (0.928g) and assumed that CdCO3 participates
in the reaction I got that the molar ratio of CdCO3 and Y is 2:5
if Y is oxygen. Still strugling to make a complete picture of
this.
#Post#: 1392--------------------------------------------------
Re: Problem of the week-19/11/12
DIR By: Michel
Date: December 3, 2012, 1:17 pm
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Damn...
Looks like this is heading to a dead end :'( :'(
I intended KClO3 to serve as 'Oxygen supplier' not a
reactant...I wanted to make it 'heated in an atmosphere of
oxygen' but i thought mixing with KClO3 wouldn't hurt...now the
problem's a bit flawed.
There was a reaction I was looking for...and it will occur if
not mixed with the KClO3, but heated in the same vessel with
KClO3.
I didn't know about the KClO3 + Na2S Reaction...so sorry guys:'(
You have your +10 Chemist@
What i intended was
Na2S + 3O2 + CO2=> Na2CO3 + SO2
Y being SO2.
This rxn will also occur in the system especially as CO2 dilutes
the O2 from KClO3, most likely, both the reactions would compete
in the vessel, ending up with a mix of more Na2SO4 and less
Na2CO3 and SO2
#Post#: 1393--------------------------------------------------
Re: Problem of the week-19/11/12
DIR By: Chemist@
Date: December 3, 2012, 1:54 pm
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--- Quote from: Michel link ---
>
> Damn...
> Looks like this is heading to a dead end :'( :'(
> I intended KClO3 to serve as 'Oxygen supplier' not a
reactant...I wanted to make it 'heated in an atmosphere of
oxygen' but i thought mixing with KClO3 wouldn't hurt...now the
problem's a bit flawed.
> There was a reaction I was looking for...and it will occur if
not mixed with the KClO3, but heated in the same vessel with
KClO3.
> I didn't know about the KClO3 + Na2S Reaction...so sorry
guys:'(
> You have your +10 Chemist@
> What i intended was
> Na2S + 3O2 + CO2=> Na2CO3 + SO2
> Y being SO2.
> This rxn will also occur in the system especially as CO2
dilutes the O2 from KClO3, most likely, both the reactions would
compete in the vessel, ending up with a mix of more Na2SO4 and
less Na2CO3 and SO2
>
>
--- End Quote ---
No problem. After all, it was very interesting solving it. And
thanks for those karmas.
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