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Offline the_little_angel

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strange reactions
« on: April 23, 2007, 11:37:03 AM »
today i did an experiment at home. It was really strange that it was a reaction of Copper oxide and H2SO4.Theoretically, there must be H2O and Sulphate Copper made from that creation. But when I fired the solution, there was something black and brown. I dipped a piece of litmus paper in it, it was crimson. Who can explain it to me?
« Last Edit: April 23, 2007, 11:56:27 AM by the_little_angel »

Offline billnotgatez

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Re: strange reactions
« Reply #1 on: April 23, 2007, 12:59:51 PM »
Copper(I) oxide (cuprous oxide, Cu2O), a red powder.
Copper(II) oxide (cupric oxide, CuO), a black powder.

Which of these did you have?
Are you sure it was pure
Was the sulfuric acid pure?
Could you write a balanced equation (just for grins)?

I am curious

Offline the_little_angel

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Re: strange reactions
« Reply #2 on: April 24, 2007, 09:11:08 AM »
i used copper(II) oxide (I think we usually think of copper(II) when we mention it without the valence). Theoretically, a reaction of an acid oxide and an acid makes a salt and water.
CuO + H2SO4 -> H2O + CuSO4
I've read a lot of books to check this equation. It exists. But I'm not sure my copper oxide and sulphuric acid are all pure.

Offline the_little_angel

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Re: strange reactions
« Reply #3 on: April 27, 2007, 10:47:54 AM »
no more explanation for this?

Offline billnotgatez

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Re: strange reactions
« Reply #4 on: April 27, 2007, 05:26:41 PM »
In this case, unfortunately I am not knowledgeable as well

I am curious

Offline the_little_angel

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Re: strange reactions
« Reply #5 on: April 28, 2007, 02:20:21 AM »
that's ok. I have one more thing to ask: what's the color of copper chloride? I combined CuO and HCl together, it made a green solution.
« Last Edit: April 28, 2007, 06:32:00 AM by the_little_angel »

Offline Donaldson Tan

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Re: strange reactions
« Reply #6 on: April 28, 2007, 03:03:47 AM »
Did you use concentrated HCl? CuCl42-[/sub] is a green complex which forms in the pressence of excess chloride ions.
"Say you're in a [chemical] plant and there's a snake on the floor. What are you going to do? Call a consultant? Get a meeting together to talk about which color is the snake? Employees should do one thing: walk over there and you step on the friggin� snake." - Jean-Pierre Garnier, CEO of Glaxosmithkline, June 2006

Offline UnintentionalChaos

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Re: strange reactions
« Reply #7 on: April 28, 2007, 04:29:59 AM »
How concentrated was the H2SO4? Anhydrous CuSO4 is white or grayish and the color could easily be affected. This would be the majority product if you used conc. H2SO4. If this is the case, dilute some in water and see if you get blue.

Offline the_little_angel

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Re: strange reactions
« Reply #8 on: April 28, 2007, 06:31:14 AM »
thanks very much. Yes, that's right, i used concentrated HCl. I couldn't explain how could CuCl2 be green instead of blue. It wasn't CuCl2, was it?

Offline UnintentionalChaos

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Re: strange reactions
« Reply #9 on: April 28, 2007, 04:16:00 PM »
In concentrated solution, a good deal of the copper (II) chloride acts like "copper (II) tetrachlorocuprate (II), which is still two copper and 4 chlorine, so the formula is the same. Tetrachlorocuprate ion I think is bright yellow and combined with the normal blue color of the water coordinated looks deep green. If you dilute the green solution, it reverts to blue as the equilibrium is shifted toward water-coordinated copper ions.

My last post was about the copper sulfate from the original question.

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