Tests for gases and anions

How would you test for the presence of hydrogen gas?

By using the 'pop' test: ignite the gas, and it should produce a popping sound.

How do you test for the presence of oxygen gas?

By placing a glowing splint in the gas; if oxygen is present, the splint will relight.

How can you test for carbon dioxide gas?

By bubbling the gas through limewater; it will turn milky if CO2 is present.

What is the test for chlorine gas?

Chlorine gas bleaches damp litmus paper, turning it white.

What is the test for ammonia gas?

Ammonia gas turns red litmus paper blue.

How do you test for the presence of sulfate ions (SO₄²⁻)?

Add barium chloride solution to the sample; if sulfate ions are present, a white precipitate of barium sulfate will form.

How do you test for halide ions (Cl⁻, Br⁻, I⁻)?

Add silver nitrate solution followed by dilute nitric acid. A white precipitate forms for chloride, a cream precipitate for bromide, and a yellow precipitate for iodide.

What is the test for carbonate ions (CO₃²⁻)?

Add dilute acid to the sample; if carbonate ions are present, carbon dioxide gas will be released.

How would you test for the presence of nitrates (NO₃⁻)?

Add sodium hydroxide solution, then aluminum foil; if nitrates are present, ammonia gas will be produced.

What is the test for chloride ions (Cl⁻)?

Add silver nitrate solution and observe the formation of a white precipitate of silver chloride.

What is the result when testing for iodide ions (I⁻) using silver nitrate?

A yellow precipitate of silver iodide forms.

How do you test for the presence of sulphite ions (SO₃²⁻)?

Add hydrochloric acid and barium chloride. A white precipitate will form if sulfite ions are present.

What color change would you expect when testing for ammonia gas with litmus paper?

Red litmus paper will turn blue.

How would you test for the presence of hydrogen chloride gas?

Pass the gas through ammonia solution, and a white smoke of ammonium chloride will form.

How do you test for phosphate ions (PO₄³⁻)?

Add ammonium molybdate and nitric acid; a yellow precipitate indicates the presence of phosphate ions.