Experimental Technique Part 1 Flashcards
What is paper chromatography used for?
Used for:
- finding out how many substances are in a mixture
- to check the purity of substance
- identify substances in a mixture based on how far they travel
The formula for Rf value (Retardation Factor)
R f value=
Dis(tan)ce travelled by sample /
Dis(tan)ce travelled by solvent
More soluble sample used on chromatography paper =?
Travels further
What is the purpose of crystallisation?
Obtain solute from solution
How to do a crystallisation experiment?
- done by heating solution until saturated, leaving it to cool to form crystals
- saturation: a solution in which no more solute dissolves
- checking for saturation: dip a glass rod in, if crystals form = saturated
What is and purpose of filtration
Method of separation to remove insoluble solid from solution leaving behind filtrate and residue that has been filtered out
Purpose of simple distillation
Obtain solvent from solution
Method of simple distillation
The solvent evaporates when heated, passes through a Liebig condenser (surrounded by a glass chamber aka water jacket) and collects in the beaker
Purpose of Fractional Distillation
To separate two miscible liquids with different boiling points
Method of fractional distillation
Heat to liquid with lower boiling point temp and it will turn to vapour and rise thru condenser.
the fractionating column separates unwanted liquid from sticking to vapour
miscible: mixes v well together
How do you tell if a substance is pure in relation to its its boiling and melting point?
Pure substances melt and boil sharply at specific temperatures.
What is gas collected based on?
Solubility & Density
How to measure volume with these apparatus from least to most accurate
pipette, measuring cylinder, burette
Measuring Cylinder -> Burette -> Pipette
What method of delivery to collect a gas that is soluble in water and denser than air?
Downward delivery
What method of delivery to collect a gas that is soluble in water & less dense than air?
Upward delivery
