Question

List at least two chemical reactions that resulted in a yellow, orange, or red precipitate. For these reactions, list the possible chemical name of the precipitate. What do these reactions (and the others with similar color reactions) have in common?

Answer 1

1) 0.2M ferric nitrate is added gradually to 1M sodium hydroxide. In result, a red precipitate appears. The precipitate is ferric hydroxide. 
2) 0.2M potassium chromate is added gradually to 0.05M lead acetate. in result, a yellow precipitate appears. The precipitate is called potassium acetate. 
The common between the two is that the colors originated from  one of the reactants.