[Karecia]

I am trying to decide if i should use potassium alum with different food coloring dyes or just use the different salts to get different color crystals. For example if i wanted to make my crystals blue should i use potassium alum with blue food coloring dye or should i make them from copper sulfate?

If there are no main reasons for any of the options would anyone know the main advantages/disadvantages of doing either?

[chenbeier]

Adding of other materials ( organic colors) to the salt solution would disturb the growing of the crystals.
For alum type Me(I)Me(III)SO₄ x 18 H₂O, exchange the Me( III) in this case Al to Cr, Fe, V, Mn, Co, and others. Me(I) can be K and to higher Alkali metals like Rb or Cs.Also NH₄⁺ or Tl can be used.

[Borek]

You can't make alum crystals from copper. Alum requires two cations - one with +1, and one with +3 charge.

Food coloring can work, but to be sure you would need to check experimentally. Generally speaking perfect crystal won't contain any other things than just the pure salt itself, so its color should be that of its components. But there is always a slight chance that the food coloring will find a way to contaminate the crystal lattice.

[Karecia]

Was deciding between either copper sulfate or alum, not both at the same time.




Thanks for the reply, guess i try it with both then