Tests for Gases & Identifying Ions

How do you test for hydrogen gas?

Hold a burning splint at the opening of a test tube containing the gas. -- Hydrogen burns with a squeaky pop.

How do you test for oxygen gas?

Insert a glowing splint into the gas. -- The glowing splint relights.

How do you test for carbon dioxide gas?

Bubble the gas through limewater (aqueous calcium hydroxide). -- The limewater turns milky/cloudy.

How do you test for chlorine gas?

Expose damp litmus paper to the gas. -- The litmus paper is bleached and turns white.

Why must litmus paper be damp when testing for chlorine?

The moisture allows chlorine to react and produce the bleaching effect.

What is a cation?

A positively charged ion.

What is an anion?

A negatively charged ion.

What is qualitative analysis?

Analysis used to identify which substances or ions are present, rather than how much is present.

What is a precipitate?

An insoluble solid formed during a reaction in solution.

What is a precipitation reaction?

A reaction in which aqueous ions combine to form an insoluble solid.