Which aqueous solution is colored

The perchlorate ion, ClO 4 — in particular, forms almost no complexes. The nitrate ion, NO 3 — , and sulfate ion, SO 4 2— , only occasionally form complexes. The addition of ligands to a solution in order to form a highly colored complex is often used to detect the presence or absence of a given metal in solution.

This can be seen in the following video, where a aqueous solution of ammonia is added to a copper sulfate solution:. When ammonia is added, a precipitate of Cu OH 2 s is formed. While most of the reactions we have been describing are very fast and occur just as quickly as the solutions are mixed, this is not always the case.

With certain types of complexes, ligand substitution is quite a slow process. Alternatively the solution may he heated, in which case the green color will usually appear within 10 min. The reaction. Ligand substitution reactions of other Cr III complexes behave similarly. Almost all the compounds which were used to establish the nature and the geometry of coordination compounds were inert rather than labile. This graphic looks at the colours of transition metal ions when they are in aqueous solution in […].

The first involves introducing transition metal or rare earth metal oxides to the glass. This is usually achieved by the addition of metal oxides to the glass.

The metal ions absorb certain wavelengths of light, varying depending on the metal, leading to the appearance of colour. Close Menu Home. Infographics Index. Like Loading Connect and share knowledge within a single location that is structured and easy to search.

While going through my AP chem prep book again, I came across questions asking about the color of certain aqueous solutions. For example:. I know that zinc compounds are generally colorless, so I picked that and it was correct , but I have no idea how to predict the colors of the rest of the compounds. So, to answer this question and questions similar to this , would I need to use pure memorization of the common elements that produce color?

There is no simple way to predict beforehand as far as I know. This is a general knowledge type of chemistry question, you will have to know or memorize the colors of common anions and cations. It will be much easier, if you do so group wise and know the colors of the first row of transition element ions. Any object which absorbs a certain portion of visible light's spectrum, will appear colored to us. For colored solutions, we will always consider absorption of light in the visible region.

So if you see a green solution, it is not reflecting green light, it is absorbing a certain portion of the visible spectrum and the transmitted light [from the solution] appears green to us.

Keep this concept in mind because a lot of students have this misconception. You should know that sulfate ion is colorless but copper II ion is blue so most likely copper sulfate solution is blue. In part c, you should know the color of potassium ion and dichromate ion and then guess the color. Do the remaining exercise for others.

It will be very difficult to predict if both ions are colored because it is not like that we are mixing two paints, a yellow paint with blue paint will show a green color. You will have to study the absorption spectrum of that salt. The theory of color of ions and that of solids is quite complex. It was developed by physicists. You can start from crystal field theory if you wish to see how the color of transition metal ions is explained but I will not recommend that you explore it if you are in school.