Chromatography and Water treatment Flashcards
Chromatography is..? What are the two phases?
A method used to separate a mixture of soluble substances and identify them. A mobile phase is where molecules can move. This is always or gas. A stationary phase is where the molecules. This can be either a solid or a very thick liquid.
In paper chromatography what is the mobile and stationary phase?
The stationary phase is a piece of filter paper and the mobile phase is a solvent.
What does the amount of time in each stage affect the phases?
- how soluble they are in a solvent
- how attracted they are to the stationary phase (filter paper)
What is the method of setting up?
You draw a line at the baseline in pencil (insoluble) andput a spot of the mixture on the line. Dip the paper in the solvent and place glass over the beaker to prevent evaporation. The solvent will start to move up the paper, taking parts of the mixture with them and will separate out. Remove the paper and draw a solvent front where the solvent reaches the top (in pencil).
How do you calculate the Rf value?
Rf value = distance travelled by solute ➗distance travelled by solvent
What are the sources of water?
- surface water> from lakes,rivers and reservoirs
- ground water> from aquifers (rocks that trap water underground)
- waste water> from water that has been contaminated by a human process.
How is water purified in water treatment plants?
1) filtration> a wire mesh that screens out large twigs etc
2) sedimentation> a chemical is added to the water which makes fine particles clump together and settle at the bottom.
3) chlorination>chlorine gas is bubbled through to kill harmful bacteria and other microbes
An alternative of gaining drinking water?
Distillation-> makes distilled water but requires loads of energy therefore it is very expensive, although in science labs you need it as it gives a pure substance that won’t give false results in reactions.
