Chemical Forums
Chemistry Forums for Students => Undergraduate General Chemistry Forum => Topic started by: Archy12345 on December 26, 2012, 05:44:04 PM
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Cu2+ + SO42- + 2Na+ + S2O32- :rarrow: Cu+ + SO42- + 2Na+ + ?
Equal parts of reactant were mixed. The oxidation of the copper is evident because of the blue to green color change. What happens to the thiosulfate anion? Does it's charge go to -1? And if so, what does the sodium end up bonding with?
I should also add that there was a sulfur colored precipitate that formed, however, the compound was not sulfur.
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You have do develop to equations.
Thiosulfat goes to sulfate
Cupper-II goes to copper-I
Precipitate of cupper-T-sulfide
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I'm guessing that for ever thiosulfate ion you'd produce two sulfate ions.
S2O3- :rarrow: 2SO42-
Does it get oxygen from the water?
And what is the T in Copper-T-Sulfide?
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Misstyping Copper-I-sulfide Cu2S was meant.
Correct the oxygen is from the water. But I would develop Sulfide and Sulfate.
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As the Cu2S was formed, the solution turned back to blue. I'm assuming this would mean that there are now Cu2+ ions back in the solution.
Would it be that all of the Cu+ ions have reacted with the Sulfide and that all that's left in the solution is Cu2+?
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I would say so. Because Cu+ is not stable in solutions. Only Oxide, Sulfide, Selenide, and (Pseudo)Halogenides are known as unsolouble. Probably some organic complex compounds.
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I had another test tube where I put an excess of Sodium thiosulfate. After the reaction was complete I had no precipitate, and the solution was a transparent brown color. I am very bewildered by this...
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Miracle, miracle. Transparent brown?
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More thiosulfate ions would mean that more of the copper was oxidized. So I would have thought that the solution would have stayed more green.
Now I took some of this brown liquid and put it in an evap dish. Heat makes the solution turn from brown to black. And the powder that was left was a lustrous black powder. I ground it up and mixed it with various things.
This powder in insoluble.
It does seem to react with HCl, but only slightly. It forms this very, very faintly tinted yellow solution. The black powder remains though.
It catalyzes the decomp of hydrogen peroxide.
And it makes KMnO4(aq) go from that purple/pink color to a colorless solution. Much the same if you have an acidified solution of hydrogen peroxide and you pour KMnO4(aq) in and it goes colorless.
What I'm gathering is that this substance has reducing properties.
I believe it's Cu2O. I've done some research and people who have done this experiment usually get a solid that forms in this solution, which would indicate Copper(I)Oxide. I'm just not sure why I didn't get any solid until I heated the solution.
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What I'm gathering is that this substance has oxidizing properties.
It reduced permanganate, so it has reducing properties, not oxidizing.
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What I'm gathering is that this substance has oxidizing properties.
It reduced permanganate, so it has reducing properties, not oxidizing.
Yes, you're right. Wasn't thinking when I wrote it. Reducing properties.
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This powder in insoluble.
It does seem to react with HCl, but only slightly. It forms this very, very faintly tinted yellow solution. The black powder remains though.
It catalyzes the decomp of hydrogen peroxide.
And it makes KMnO4(aq) go from that purple/pink color to a colorless solution. Much the same if you have an acidified solution of hydrogen peroxide and you pour KMnO4(aq) in and it goes colorless.
I think its still coppersulfide. But here more CuS as Cu2S. Black color indicate it. The Cu+ is orange red either Oxide or Sulfide.
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I think you're right about the brown solution containing Copper (II) Sulfide....but I'm not sure about the first solution having Cu2S since the precipitate is a bright yellow. Almost sulfur colored. Haven't done any tests on it though.
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In acidic conditions Thiosulfate decompose and sulfur is one of the products.