Tests for Cations

How do we test for positive Ions?

How do we test for positive Ions?

1. Dip a NiCr wire into dilute HCL

2. Form a metal loop with the wire and apply sample salt

3. Put loop in bunsen burner and observe colour change

What colour does Lithium go?

Crimson

What colour does Sodium go?

Yellow

What colour does Potassium go?

Lilac

What colour does Calcium go?

Orange

What colour does Copper go?

Green

How do we test for Positive Ions with Sodium Hydroxide?

1. Add a few drops of Sodium Hydroxide solution on to the sample salt

2. Observe colour change of formed precipitate

What colour does Fe²⁺ go?

Green

What colour does Fe³⁺ go?

Red

What colour does Cu²⁺ go?

Blue

How do we test for Ammonium (NH⁴⁺) Ions?

1. Add a few drops of sodium hydroxide solution

2. Use Damp Red Litmus paper if it turns blue it is positive