Tests for Negative Ions

Testing for Carbonates:

• Test for carbon dioxide (CO2)
• Bubble the gas produced through lime water
• The limewater turns cloudy if carbon dioxide is present 

We tests for CO2 because carbonate ions (CO3 2-) react with dilute acids to form CO2

ACID + CARBONATE --> SALT + WATER + CARBON DIOXIDE

Testing for Halides:

• Chloride (Cl-), Bromide (Br-)…