Prep for Chemistry test

Prep for Chemistry test

1. Chromatography

   • separate mixtures of soluble substances
   • The Mobile Phase
     • is the solvent that moves through the paper
     • carrying different substances with it
   • The Stationary Phase
     • which in paper chromatography is very uniform
     • absorbent paper

2. Pure substances

   • a pure substance consists only of one element or one compound

3. mixtures

   • a mixture consists of two or more different substances, not chemically joined together

4. Separating mixtures

   • Mixtures can be separated by physical processes
   • These processes do not involve chemical reactions
   • no new substances are made

5. Filtration

   • Filtration is used to separate an insoluble solid from a liquid
   • It is useful for separating sand from a mixture of sand and water
   • Filtration works because the filter paper has tiny holes or pores in it
   • These are large enough to let small molecules and dissolved ions through

6. Crystallisation

   • Crystallisation is used to produce solid crystals from a solution
   • When the solution is warmed, some of solvent evaporates leaving crystals behind
   • crystallisation is used to obtain copper sulfate crystals from copper sulfate solution.

7. Simple distillation

   • Simple distillation is used to separate a solvent from a solution
   • Simple distillation works because the dissolved solute has a much higher boiling point than the solvent
   • he remaining solution becomes more concentrated as the amount of solvent in it decreases

8. Fractional distillation

   • Fractional distillation is used to separate different liquids from a mixture of liquids.
   • It is useful for separating ethanol from a mixture of ethanol and water, and for separating different fractions from crude oil.
   • Fractional distillation works because the different liquids have different boiling points