Australia's Science Forum

I have been asked for some strong coloured solutions that can be boiled down safely to leave a solid behind. I can think of Copper Sulfate solution, coloured salt water. Can anyone please tell me some other solutions that would be suitable.

Thanks,
Jodie

Soft drinks work ok but instead of a solid you often get a sticky syrup. Be careful when boiling copper sulfate as the fumes are toxic. It needs to be turned off well before all the liquid has gone and let the heat from the evaporating basin finish it off. Reheat if necessary. We had quite a few kids one year who couldn't follow instructions and we had to evacuate the classroom and I think 4 or 5 kids went to sick bay with breathing difficulties and headaches.

We regularly boil off copper sulphate solutions until the solid residue remains. I havent heard that the fumes are toxic and we have never had any sick children as a result. I know that one should avoid breathing in the dust of copper sulphate but I hadnt heard of avoiding fumes, I was always under the impression that only the water was evaporated off and the copper sulphate remained in the evaporating dish. I cant find anything in the msds about it either. Does anyone have any further info??

We us a strong salt solution with food colouring works well

Hi All,

Nickel Sulfate gives a green solid after evap.

Cheers,

Robb.....