Chemical Analysis & Instrumental Analysis Flashcards
Artificial colours can be separated using _____ ____________.
Paper chromatography
Why do people use paper chromatography?
To see which dyes/colours are in a food colouring.
How do you carry out paper chromatography?
1) Extract the food colouring by placing it in a cup with a few drops of solvent (water).
2) Put spots of the coloured solution on a pencil line on filter paper. USE PENCIL NOT PEN, PEN WILL FUCK IT UP.
3) Roll up the sheet and place it in a beaker with some solvent - make sure the pencil line is above the solvent tho.
4) The solvent will seep up the paper, taking the dyes in the food colouring with it.
Different dyes stop at ________ points along the chromatography paper.
Different Points.
A chromatogram with 4 spots on it means there’s how many dyes present?
At LEAST 4, there could be more because different dyes could’ve stopped at the same point.
Advantages of using machines to analyse unknown substances, list 3.
- Sensitive - can detect even the tiniest amounts of substances.
- Very fast - tests can be automated.
- Very accurate
What does gas chromatography do?
Separates out a mixture of gases and helps you identify unknown substances.
Describe Gas Chromatography.
1) A carrier gas is used to carry substances through a column packed with a solid material.
2) The different substances travel through the tube at different speeds, so they’re separated.
3) The amount of time they take to reach the detector is called the retention time. The retention time is what helps to identify a substance.
4) The recorder draws a gas chromatograph, the number of peaks = the number of different compounds in the sample.
5) Position of the peaks = retention time
What’s GC-MS?
Gas Chromatography Mass Spectrometry
GC-MS is more accurate than just GC, how?
You can work out the relative molecular mass of each of the substances present in the graph it draws, just read them off the molecular ion peak.
