Mixtures and Chromatography Flashcards
What is a mixture?
A mixture is a substance formed from two or more elements that aren’t chemically bonded together.
What is a physical method?
A physical method is one that doesn’t involve a chemical reaction, so it doesn’t form any new substances.
Name examples of physical methods?
Some examples are filtration, crystallisation, simple distillation and fractional distillation.
What is air a mixture of?
Air is a mixture of gases such as (mainly) nitrogen, oxygen, carbon dioxide and argon.
What is crude oil a mixture of?
Crude oil is a mixture of different length hydrocarbon molecules.
What is chromatography?
Chromatography is a technique to separate different dyes in an ink.
How do you do chromatography?
1) Draw a line near the bottom of a sheet with filter paper with a pencil - pencil marks are insoluble and won’t dissolve in the solvent.
2) Add a spot of ink to the line and place the sheet in a beaker of solvent
3) Make sure the ink isn’t touching the solvent.
4) Place a lid on top of the container to stop the solvent from evaporating.
5) The solvent seeps up the paper carrying the ink with it.
6) Each different dye in the ink will move up the paper at a different rate so the dyes will separate out. Each dye will form a spot in a different place.
7) If any of the dyes in the ink are insoluble in the solvent you’ve used, it will stay on the line.
8) When the solvent has nearly reached the top of the paper, take the paper out of the beaker and leave it to dry.
What is the end result called?
The end result is called a chromatogram.
What does insoluble mean?
It means that it won’t dissolve.
Why shouldn’t you use a pen to draw a line on the filter paper for chromatography?
Because pen marks are soluble and will dissolve in the solvent.
