Chemistry Practicals / SPA:
Recently, i received several enquiries and questions from students on the color of copper hydroxides and copper carbonates.
I understand why the confusion. This is because in the local Secondary Schools, many of the Science (Chemistry) teachers are only showing the students of the Blue Color PPT when they test for the Cu2+ cation using alkaline solution such as dilute NaOH or aqueous Ammonia Solution. The Blue Color PPT are due to the formation of insoluble Copper Hydroxide which is very distinct.
Many of students are confused and thought all Copper Salts have a Blue Color PPT. This is certainly NOT TRUE.
Summary on Color & Form of Common Copper Salts:
* Copper Hydroxide –> Insoluble Blue Color Precipitates (PPT)
* Copper Carbonate –> Insoluble Green Color Powders
* Other soluble copper salts –> Blue Color Solutions
Below is the appearance of Copper Carbonate powder:
Hope this post helps you in some ways! =)