Chemical Analysis and Instrumental Methods

Beschreibung

GCSE Science (Chemistry Additional) Mindmap am Chemical Analysis and Instrumental Methods, erstellt von sian.allison am 24/01/2014.
sian.allison
Mindmap von sian.allison, aktualisiert more than 1 year ago
sian.allison
Erstellt von sian.allison vor fast 11 Jahre
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Zusammenfassung der Ressource

Chemical Analysis and Instrumental Methods
  1. Artificial Colours can be seperated using paper chromatography
    1. A food colouring might contain one dye or it might be a mixture of dyes
      1. 1. Extract the colour from a food sample by placing it in a small cup with a few drops of slovent (water, ethonal etc)
        1. 2. Put spots of the coloured solution on a pencil baseline on filter paper
          1. 3. Roll up the sheet and put it in a beaker with some solvent - but keep the baseline above the level of solvent
            1. 4. The solvent seeps up the paper taking the dyes with it. Different dyes form spots in different places
              1. 5. Watch out though a chromatogram with four spots means at least four dyes not exactly four dyes. There could be five dyes with two of them making a spot in the same place
      2. Machines can also analyse unknown substances
        1. You can identify elements and compounds using instrumental methods
          1. Advantages
            1. Very sensitive can detect even the tiniest amount of substance
              1. Very fast and tests can be automated
                1. Very accurate
            2. Gas chromatography
              1. Seperate out a mixture of compounds to help identify the substances
                1. 1 .A gas is used to carry substances through a column packed with a solid material
                  1. 2. The substances travel through the tube at different speeds so they are seperated.
                    1. 3. The time they take to reach the detector is called retention time. It helps identify substances
                      1. 4. The recorder draws a gas chromatograph. The number of peaks shows the number of different compounds in the sample
                        1. 5. The position of the peaks shows the retention time of each substance
                          1. 6. The gas chromatography column can also be linked to a mass spectrometer. This process is known as GC-MS and can identify the substances leaving the column very accurately
                            1. 7. You can work out the relative molecular mass of each substance from the graph it draws. You just read off from the molecular ion peak
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