C5 Detective Chemistry Flashcards
draw and label a diagram of FILTRATION
when is this used?
removing insoluble solid from solvent (using filter paper)
draw and label a diagram of EVAPORATION/CRYSTALLIZATION
when is this used?
removing soluble solid from solvent (using heat)
draw and label a diagram of DISTILLATION
when is this used?
separating LIQUID with DIFFERENT BP
using vaporization+condensation
what is the use of paper chromatography?
separate + identify substances in a mixture
why does paper chromatography work?
different pigments are soluble at different points and move at different rates
draw and label a diagram of PAPER CHROMATOGRAPHY
how do you calculate Rf?
distance moved by substance/distance moved by solvent
why do PURE substances have FIXED m/b points?
same molecules → same forces between molecules
what does IMPURITY do to the MP of a solid? why?
decrease
disrupts the usual pattern of intermolecular forces → molecules less tightly held → less energy needed to overcome the forces
what does IMPURITY do to the BP of a liquid? why?
increases
extra intermolecular forces → more energy needed to overcome the forces
draw and label a diagram of FRACTIONAL DISTILLATION
when is this used?
to separate two liquids with CLOSE BP
why is fractional distillation more accurate?
FRACTIONATING COLUMN with glass beads
• hotter at the base than top
• vapor with higher bp condense inside the column and drop back down into the flask
•only vapor with lower bp can escape into condenser
what are the three different methods of GAS COLLECTION?
- upward delivery - gas less dense than air
- downward delivery - gas more dense than air
- over water - gas insoluble in water
what colors are their FLAMES:
- lithium
- sodium
- potassium
- copper
Li - red
Na - yellow
K - purple/lilac
Cu - green-blue
how do you identify the cations:
- copper
- iron (II)
- iron (III)
- zinc
- ammonium
- nitrate
how do you identify the anions:
- carbonate
- sulphate
- chloride
- bromide
