You enter a laboratory after a class has completed the Fountain experiment. How will you be able to tell whether the gas used in experiment was hydrogen chloride or ammonia?
When ammonium hydroxide is added to a solution B, a pale blue precipitate is formed. The pale blue precipitate dissolves in excess of ammonium hydroxide to give an inky blue solution. What is the cation (positive ion) present in solution B? What is the probable colour of solution B?
Answer
The cation is $Cu^{2+}$ ion. Solution B is copper sulphate. It is bright blue in colour.