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Topic: copper carbonate and sodium sulphate  (Read 5562 times)

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Offline antimatter101

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copper carbonate and sodium sulphate
« on: November 27, 2012, 09:52:23 PM »
I mixed sodium carbonate and copper sulphate together to form copper carbonate (insoluble) and sodium sulphate solution. Strangely the copper carbonate vanished into the sodium sulphate solution though it was insoluble. All carbonates are insoluble except for sodium carbonate, potassium carbonate and ammonium carbonate. Yet how come copper carbonate dissolved into sodium sulphate solution?

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Offline Hunter2

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Re: copper carbonate and sodium sulphate
« Reply #1 on: November 28, 2012, 12:48:39 AM »
How acidic was the solution.? Normally you should get a precipitation.

Offline antimatter101

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Re: copper carbonate and sodium sulphate
« Reply #2 on: November 28, 2012, 02:06:57 AM »
I didn't add any acids or bases in the experiment.
I forgot to tell you precisely what happened.
First, the solution turned green, then brown in many regions. ( I have no idea). There was no precipitate so I thought it was in suspension and filtered the solution with filter paper. The liquid that dripped out of the filter paper was brownish, for some reason. Green goo collected in the filter paper which was definately copper carbonate, but green goo? Copper carbonate is insoluble!

Does anyone know what might have caused the brown stuff? Thnks. :)

Offline Hunter2

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Re: copper carbonate and sodium sulphate
« Reply #3 on: November 28, 2012, 02:22:25 AM »
Are you sure you had copper sulfate and not iron sulfate.  Braunish color cannot obtained from cuppersulfate.

Offline Borek

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Re: copper carbonate and sodium sulphate
« Reply #4 on: November 28, 2012, 03:51:02 AM »
How pure were your reagents? How pure was the water used to prepare solutions? Have you prepared the solutions by yourself?

Also note soluble/insoluble is not a yes/no idea. There are varying levels of solubility and to some extent all salts are soluble in water. Plus, when you mix copper salt with carbonates chances are you are producing basic carbonate, not just carbonate.
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Offline antimatter101

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Re: copper carbonate and sodium sulphate
« Reply #5 on: November 28, 2012, 04:08:02 AM »
I am pretty sure it was copper sulfate. it was said on the label. I used common tap water for the experiment. Is it pure enough?

Offline Hunter2

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Re: copper carbonate and sodium sulphate
« Reply #6 on: November 28, 2012, 04:13:43 AM »
I am pretty sure it was copper sulfate. it was said on the label. I used common tap water for the experiment. Is it pure enough?

Tap water can have iron, depending on the pipework and source. Repeat it with DI-water.

Offline AWK

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Re: copper carbonate and sodium sulphate
« Reply #7 on: November 28, 2012, 04:58:13 AM »
This is well known fact in qualitative inorganic analytical chemistry that basic copper carbonate dissolves in an excess of Na2CO3 or K2CO3.
In water solution neutral CuCO3 cannot be obtained.
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Offline antimatter101

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Re: copper carbonate and sodium sulphate
« Reply #8 on: November 28, 2012, 05:13:52 AM »
Wait...wait

When I heated the green goo under the heat lamp, fine particles of green began to arrange themselves into a pattern. It's crystallising! Later I will get the solid in no time.
Does that mean that the copper carbonate was in a suspension? The suspension had to be very complete to trick me into believing that the copper carbonate has dissolved.
Where do I get distilled water, by the way?

Offline Hunter2

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Re: copper carbonate and sodium sulphate
« Reply #9 on: November 28, 2012, 07:00:30 AM »
Distilled water can be bought in shops which sell auto parts. Also some supermarket have it for the water used in an iron for clothes.

Offline antimatter101

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Re: copper carbonate and sodium sulphate
« Reply #10 on: November 28, 2012, 07:19:38 PM »
Are there any more substances where copper carbonate is soluble in? Just to remind you the copper carbonate was in sodium sulphate solution in the experiment.

Offline AWK

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Re: copper carbonate and sodium sulphate
« Reply #11 on: November 29, 2012, 04:33:10 AM »
Try ammonia.
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Offline antimatter101

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Re: copper carbonate and sodium sulphate
« Reply #12 on: November 29, 2012, 06:07:11 AM »
Strange... The crystals I collected could only PARTially dissolve in water when I added water to them after the experiment.

By the way, is iron (II) carbonate reddish-brown?

Offline AWK

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Re: copper carbonate and sodium sulphate
« Reply #13 on: November 29, 2012, 07:32:11 AM »
It is a little chance that you obtained FeCO3.
It can be easily oxidised with air to Fe(III).
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Offline antimatter101

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Re: copper carbonate and sodium sulphate
« Reply #14 on: November 29, 2012, 11:40:47 PM »
You know why I asked for the colour of iron carbonate? tHAT Was because I wanted to find out whether iron carbonate could be brown and make the solution that colour and so I mixed sodium carbonate and iron sulfate together. The precipitate was very greenish-black at first but when it dried it became reddish-brown. You say that FeCO3 can be oxidised by air, but into what? I need to know what chemical my precipitate has become.

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