Edexcel iGCSE Chemistry

Just the simple things that you need to know for paper 1 & 2.

Litmus Paper Colour Change (Acid-Alkali)

Red-Blue

Phenolphthalein Colour Change (Acid-Alkali)

Colourless-Pink

Methyl Orange Colour Change (Acid-Alkali)

Red-Yellow

Flame Test

Lithium

Crimson Red

Flame Test

Sodium

Yellow

Flame Test

Potassium

Lilac

Flame Test

Calcium

Brick Red

Flame Test

Copper(II)

Blueish green

What is the test for Ammonia?

Damp red litmus paper → blue

What is the test for Ammonium?

NaOH, then damp red litmus paper → blue

What is the test for Chlorine?

Bleaches damp blue litmus paper → white

What is the compound that tests for Anions (Negative Ions)?

AgNO₃ / Silver Nitrate

Test for Halide Ions - Cl^-, Br^-, I^-

HNO3 + AgNO3 → white/cream/yellow precipitate

Test for Sulfate Ions (SO₄^2-)

HCl + BaCl₂ → white precipitate

Test for Carbonate Ions (CO₃^2-)

HCl → Fizzing of CO₂

Test for Iron(II) Ions

NaOH → green precipitate

Test for Iron(III) Ions

NaOH → red precipitate

General Steps for Crystallisation (pure, dry crystals from…)

Heat until crystallisation point. Leave to crystallise. Pour off excess liquid. Leave crystals to dry in a warm place.