Decomposition reactions Y9

[bindi]

Hi all,
Im looking for an alternative to the heating of CuCO3 in side arm test tubes and collectiong CO2 into limewater. We are finding that the bottoms of the side are test tubes are melting and some are cracking. (I have checked to see if they are heat proof and yes they are but just cheap junk)

[rae]

I gave up using the side arms for that very reason. I now use good test tubes with a cork in the top with a glass tube through it and a rubber hose and glass tube at the other end that we then put in to the limewater. Hope that makes sense!

[Robb]

Hi All,

Try a Mecka burner, use a boiling tube (larger diameter T.Tube) and a little Copper Carbonate (Just to cover the bottom) the heating problem your getting is that the Copper carbonate is converting to Copper Oxide and the left ofer carbonate the kids are trying to decompose, the problem with that is the copper oxide has a much high melting point therefore the t.tubes are melting where really..... not much more Carbonate will be converted.

If you use a little copper carbonate it will all go to completion....
Just a variation on this prac, when the coper oxide has been converted use a little conc sulfuric (teacher only though) to convert the copper oxide to copper sulfate.

Therefore you have Copper Carbonate -----> Copper Oxide -----> Copper Sulfate.

The reacxn is slow but it does convert all oxide to the sulfate.

Let me know how it goes.

Cheers,

Robb.....

[Shas]

could someone help pls...........
decomposition is flavour of the month here at the moment. had a teacher who had converted CuO with sulfuric acid to copper sulfate. her method said to then filter and heat to evapourate water. the heating generated copious amount of vapour - not just water vapour.
I'm at a loss to know what the fumes may have been. i've ruled out contamination of evap basin, as all 3 had same result.

can anyone in knowledgeable chem talk land have a suggestion?

Thanks for any help?
Sharon

[lada]

It will be excess sulfuric acid evaporating and forming sulfur based oxides (maybe SO2 ) . Must be done in fumecopboard.
Lada

[Shas]

Thanks Lada. all makes so much sense when you have such cluey people at their computers.

Shas