Please enable JavaScript.

Coggle requires JavaScript to display documents.

Chemistry Paper 2 - Coggle Diagram

- - - - Quicker
      - More sensitive (produce a higher response from the same amount of concentration)
      - More accurate
  - - - 1.) Sterilise a nichrome wire by dipping it in hydrochloric acid and then use a bunsen burner
      - 2.) Dip the wire into the compound you want to test
      - 3.) Hold the wire near the blue part of the flame (it's the hottest part of the bunsen burner)
      - 4.) See what colour is produced
    - - Potassium → Lilac
      - Calcium → Orange/Red
      - Sodium → Yellow
      - Lithium → Crimson red
      - Copper → Green
    - - Metal hydroxide test
        
        React solution with sodium hydroxide and see what colour ir turns. This process is used as some metal ions form coloured precipitates when they react with hydroxide ions
        
        Results
        
        Fe (II) → green
        
        Fe (III) → brown
        
        Ca → white
        
        Mg → white
        
        Al →colourless (until excess NaOH is added then it turns white)
        
        Cu → blue
  - - - Carbonate + Acid → Salt + Carbon dioxide + water
      - The test for carbon dioxide is easy, simply bubble limewater through the substance and if it turns cloudy limewater is present
    - - Another type of anion
      - Results
        
        Add barium chloride which contains barium ions
        
        If sulfate ions are present, Barium Sulfate will form which is a white precipitate
        
        Add dilute hydrochloric acid (to remove impurities)
      - Barium reacts with sulfates to form insoluble white barium sulfate
    - - Anions from the 'halogen' group in the periodic table
      - Works in a similar way to the sulfate test
      - Process
        
        Add dilute nitric acid (to remove impurities)
        
        Add silver nitrate, which contains the ions that can form a white precipitate
        
        nitric acid is used NOT hydrocloric acid because it contains chloride ions which would react with the silver ions giving a false test*
      - Results
        
        Bromide → cream precipitate
        
        Iodide → yellow precipitate
        
        Chlorine → white precipitate
  - - - Bring some damp litmus paper near the sample
      - If chlroine is present the blue paper will be bleached
      - Add sample gas to a test tube
      - Initially the paper will turn red as hydrochloric acid is produce (the chlorine gas reacts with the water), then it will turn white
    - - Present a glowing splint to the sample of gas
      - If oxygen is present then the splint will re-light
      - Add the sample gas to a tes tube
      - This happens because of combustion which could only happen if the sample gas contained oxygen
    - - Bring a lit splint near the sample
      - If hydrogen is present in the sample, you should hear a squeaky pop
      - Add the sample gas to a test tube
      - This is because the energy from the flame us mixing with the hydrogen which forms water
    - - Add the gas sample to a test tube
      - Connect the gas sample to another test tube that contains some limewater
      - Bubble the gas sample with limewater
      - If carbon dioxide is present the limewater will begin to turn cloudy as solid calcium hydroxide particles form