For this I/GCSE Chemistry blog post, we will be looking at how to carry out experiments solely for cations.
Tests for Cations
Lithium- crimson red flame
Sodium- yellow orange flame
Potassium- lilac flame
Calcium- brick red flame
To do these tests you need a clean platinum loop
- to know its clean add HCl and then burn it until the flame is transparent, then you can dip it into the sample.
Many metal hydroxides are insoluble and precipitate out of solution when formed- they have characteristic colours. So you add a few drops of NaOH forming a insoluble hydroxide.
Cu + 2OH - Cu(OH)2 = Blue
(II)Fe + 2OH - Fe(OH)2 = Studgy green
(III)Fe + 3OH - Fe(OH)3 = reddish brown
You can check fro ammonia gas (NH3) using a damp piece of red litmus paper, if there is ammonia present it will turn blue.
- Ammonia gas is also smelly but it's not a good idea to smell it as its very harmful to your eyes
That is all for this post!
References:
https://www.google.com/url?sa=i&url=https%3A%2F%2Fwww.revisechemistry.uk%2FGCSE%2FAQA%2FC8-ChemicalAnalysis%2Ftestingforions.html&psig=AOvVaw3npkArRVRkkS31bB3JCFeM&ust=1627960115280000&source=images&cd=vfe&ved=0CAsQjRxqFwoTCPi7u-mukfICFQAAAAAdAAAAABAD
https://www.google.com/url?sa=i&url=https%3A%2F%2Fncert.nic.in%2Fpdf%2Fpublication%2Fsciencelaboratorymanuals%2FclassXII%2Fchemistry%2Flelm107.pdf&psig=AOvVaw0uhUqFlOUZbhLNqaL3nDRI&ust=1627960170829000&source=images&cd=vfe&ved=0CAsQjRxqFwoTCKjQ4K-ukfICFQAAAAAdAAAAABAS