Criteria of Purity Flashcards
in a chromatogram, why do different dyes travel different distances?
due to their different solubilites
the dyes that travel further up the paper are ______________
more soluble in the solvent
what is the line called that is the distance travelled by the solvent?
solvent front
how do you calculate retention factors?
rf= distance travelled by substance divided by distance travelled by solvent
why can rf values only be smaller or equal to 1?
the substance/dye can never travel further than the solvent
how can colourless liquids be seperated by chromatography?
the same way, but using a UV light to identify where spots are
how can you test the purity of a liquid?
-by it‘s boiling point
how do you know a substance is pure?
it‘s melting/boiling point is exact/sharp
how can you check for the purity of a solid?
- test it‘s melting point
the melting points and boiling points can be checked by the _____ _____
literature value
pure water boils at _____ but if salt is added to it the water boils at ____
100C, 103C
ice melts at ____ but if salt is added, the ice melts at ____
0C, -4C
what is a suitable solvent?
a solvent which can dissolve the solid
