Question

I've read somewhere that reacting the two will give a white solid and a yellow solution. I'm assuming the white solid is the silicon dioxide, but what is the chemical origins of the yellow colour of the solution?

Answer 1

The yellow color in the solution is likely due to chemical reactions involving sulfur compounds or the presence of copper (II) ions, which could arise during the reduction of copper sulfides or the oxidation of sulfur compounds in reactions similar to those that produce silicon dioxide.

Step-by-step explanation:

The yellow color of the solution you are referring to is likely due to the oxidation states of the substances involved in the reaction.

When silicon dioxide reacts as a Lewis acid, it accepts a pair of electrons from a Lewis base like the oxide ion. In a separate process, the reduction of Cu2S or copper (I) sulfide, involves blowing air through molten material, leading to the formation of copper (II) ions.

The presence of copper (II) ions in a solution often imparts a blue to green coloration. However, if the sulfur compounds are further oxidized to sulfuric acid, they can lead to a yellow color in the presence of trace amounts of copper.

Other reactions that cause color changes include the reaction of lead (II) nitrate and potassium iodide, which forms a yellow precipitate.

Similarly, the reaction of cesium oxide with water forms a basic solution of cesium hydroxide, while sulfur trioxide forms sulfuric acid. These different reactions exhibit the various color changes that can occur due to chemical processes.

It's important to note that the exact source of the yellow color in your specific context might vary based on additional components in the reaction mix or the process environment.

Without more information, it's difficult to determine the precise cause of the yellow color in the solution you mentioned.