University:
University of Cambridge
Course:
0620 IGCSE | Chemistry
Academic year:

2023
Views:

78

Pages:

3
Author:

JackA1

IGCSE Coordinated Science:Identification of Ion and Gases Identification of Ion and Gases 1. Use the following tests to identify: Aqueous cations: ● Ammonium, copper(II), iron(II), iron(III) and zinc by means of aqueous sodium hydroxide and aqueous ammonia as appropriate. Cation Test What happens if cation is present? Ammonium (NH4+) Add dilute sodium hydroxide, and then heat gently. Damp red litmus paper turns blue and ammonia gas is released. Copper (II) Add dilute sodium hydroxide OR ammonia solution Pale blue precipitate forms.However, as you add more ammonia, the solution dissolves, leading to a deep blue solution. Iron (II) Add dilute sodium hydroxide OR ammonia solution. Pale green precipitate forms. Iron (III) Add dilute sodium hydroxide OR ammonia solution. Red-brown precipitate forms. Zinc Add dilute sodium hydroxide OR ammonia solution White precipitate forms. Anions: ● ● ● ● Anion Carbonate by means of dilute acid and then limewater, Chloride by means of aqueous silver nitrate under acidic conditions, Nitrate by reduction with aluminium, Sulfate by means of aqueous barium ions under acidic conditions, Test What happens is anion is present? Carbonate Add dilute hydrochloric acid Anion is present if bubbles give off gas that turns limewater milky 1. Add same amount of nitric acid as the chloride 2. Add silver nitrate solution Chloride Chloride ions will form a white precipitate. Nitrate Add sodium hydroxide.Afterwards, add some pieces of aluminum Nitrate ions are present if ammonia gas is given off. Sulfate Add same amount of dilute hydrochloric acid.Next, add Barium Nitrate solution. White precipitate will form if Sulfate ions are present. Gases: ● ● ● ● ● Ammonia by means of damp red litmus paper, Carbon dioxide by means of limewater, Chlorine by means of damp litmus paper, Hydrogen by means of a lighted splint, Oxygen by means of a glowing splint. Gas Test What happens if gas is present? Ammonia, NH3 Use damp red litmus paper Indicator turns blue Carbon Dioxide, CO2 Bubble the suspected Carbon Dioxide sample through limewater. Limewater becomes cloudy or milky. Chlorine, Cl2 Hold damp litmus paper in the gas. Paper turns white. Hydrogen, H2 Put the gas in the tube and hold a lighted splint into the tube. Gas burns with a squeaky pop Oxygen, O2 Collect the gas in a test tube and hold a glowing splint next to it. Splint relights.