Many students are familiar with the chapter on Qualitative analysis. Most will be able to rattle of the top of their heads very quickly, the colour of precipitates. For instance, copper(II) hydroxide is a blue precipitate, iron(II) hydroxide is a dirty green precipitate and iron(III) hydroxide is a reddish brown precipitate.
What I’ve found however, is that many students are not too familiar with identifying coloured solutions.
Here are the 3 most popular coloured solutions in the Pure/Combined Chemistry syllabus that you need to know if you are taking your O Level Chemistry soon!
- Blue solutions. Solutions that are blue in colour usually contain Cu2+ ions. Think copper(II) sulfate, copper(II) chloride, copper(II) nitrate solutions etc…
- Green solutions. Solutions that are green in colour usually contain Fe2+ ions. Think iron(II) sulfate, iron(II) chloride, iron(II) nitrate solutions etc..
- **Yellow solutions. Solutions that are yellow in colour usually contain Fe3+ ions. Yes. You read that right. Yellow. NOT reddish brown, NOT brown. This is by far one of the coloured solutions that students FAIL to identify correctly!
I hope this short post has helped make it easier for you to identify and work with coloured solutions!