Testing For Negative Ions

The video tutorial explains how to test for carbonate, sulfate, and nitrate ions. For carbonates, dilute acid is added, and the gas produced is bubbled through lime water, turning it milky if carbonates are present. Sulfates are tested by adding barium chloride, forming a white precipitate of barium sulfate. Nitrates are tested by adding sodium hydroxide and aluminum powder, which reduces nitrates to ammonium ions, releasing ammonia that turns litmus paper blue. The video also covers writing and balancing chemical equations for these reactions.

What is the visual indication that carbon dioxide is produced when testing for carbonate ions?

• The solution turns blue.

• Lime water becomes milky.

• The solution bubbles vigorously.

• A red precipitate forms.

Which chemical is added to test for the presence of sulfate ions?

• Sodium hydroxide

• Barium chloride

• Aluminum powder

• Hydrochloric acid

What is the white precipitate formed when testing for sulfate ions?

• Barium sulfate

• Calcium carbonate

• Sodium sulfate

• Ammonium chloride

Which substance is used to reduce nitrate ions during the test for nitrates?

• Lime water

• Barium chloride

• Sodium hydroxide

• Aluminum powder

How can the presence of ammonia be confirmed during the nitrate test?

• By observing a color change in lime water

• By the solution turning green

• By the formation of a white precipitate

• By using damp red litmus paper