Edexcel IGCSE Chemistry - Chemical Tests

Flashcards covering chemical tests for gases, cations, anions, and water purity.

What is the test for hydrogen gas?

Use a burning splint; it creates a ‘squeaky pop’ sound.

How can you test for oxygen gas?

Insert a glowing splint into the test tube; the splint relights in oxygen.

What indicates the presence of carbon dioxide gas?

Bubble the gas through limewater, which will turn milky.

What occurs when ammonia is tested with damp red litmus paper?

The paper turns blue.

How is chlorine gas detected using litmus paper?

Damp litmus paper turns white when exposed to chlorine gas.

How is a flame test carried out?

Take a sample of the metal on a wire and put it in a flame; the color change indicates the metal.

What color does lithium produce in a flame test?

Red.

What color does sodium produce in a flame test?

Yellow.

What color does potassium produce in a flame test?

Lilac.

What color does calcium produce in a flame test?

Orange-red.

What color does copper produce in a flame test?

Blue-green.

What is the method to test for ammonium ions (NH4+) using NaOH?

NH4+ reacts with NaOH to form NH3(g), which turns damp red litmus paper blue.

What precipitate is formed when copper(II) ions are treated with NaOH?

A blue precipitate.

What precipitate is formed when iron(II) ions are treated with NaOH?

A green precipitate.

What precipitate is formed when iron(III) ions are treated with NaOH?

A brown precipitate.

How are halide ions tested?

Add dilute nitric acid followed by silver nitrate; chloride gives a white precipitate, bromide gives a cream precipitate, iodide gives a yellow precipitate.

What indicates the presence of sulfate ions using barium chloride?

A white precipitate will form when sulfate ions are present after adding dilute hydrochloric acid.

How do carbonate ions react with acids?

Carbonates react with dilute acids to produce carbon dioxide gas, which can cloud limewater.

What color change indicates the presence of water using anhydrous copper(II) sulfate?

Anhydrous copper(II) sulfate turns from white to blue.

What physical test can determine the purity of water?

Evaporate the water or measure its boiling point.