Testing for ammonium ions

Question 1

What test is used to test for cations?

Answer 1

Test for ammonium ions

Question 2

What gas is produced when ammonium containing salts are heated with aqueous hydroxide?

Answer 2

Ammonia gas

Question 3

Write the ionic equation for the reaction between ammonium and aqueous hydroxide

Answer 3

NH4+ (aq) + OH- (aq) → NH3 (g) + H2O (l)

Question 4

What is the ammonia that is formed in the reaction between ammonium and aqueous hydroxide?

Answer 4

Alkali and gas

Question 5

What is the method to test for ammonia in the test for ammonium ions?

Answer 5

Aqueous sodium hydroxide is added to the solution we want to test for ammonium ions
To allow the ammonia to be released as a gas we have to heat the mixture (in a water bath or with a Bunsen burner)
The mixture does not present gas with bubbles as ammonia is much more soluble in water than carbon dioxide
If ammonium ions are present the gas that is released is alkali and we test for this using moist pH indicator paper (turns blue)