Chapter 3 Flashcards
What is a pure substance?
A substance composed of one single element or compound. It is not mixed with any other substance.
When is filtration used?
When separating insoluble solid particles from a liquid.
When is filtration used?
When separating insoluble solid particles from a liquid.
When is filtration used?
When separating insoluble solid particles from a liquid.
What occasion is evaporation to dryness used?
To obtain a soluble solid from a solution by heating the solution until all the solvent has boiled off. (for thermally stable substances like NaCl)
When is crystallisation used? Give one example of a substance obtained through this method.
To obtain a pure solid sample from its solution. (typically thermally unstable substances like copper(II) sulfate)
How do we separate a mixture of two solids?
We use a solvent in which only one solid is soluble. (The other solid is insoluble.)
When is sublimation used?
To separate a solid that sublimes from one that does not.
When is a magnet used?
To separate magnetic substances from non-magnetic substances.
When is simple distillation used?
To separate a pure solvent (liquid) from a solution.
When is a separating funnel used?
To separate immiscible liquids.
When is fractional distillation used?
To separate a mixture of miscible liquids with different boiling points.
When is chromatography used?
To separate two or more components that dissolve in the same solvent.
What is a chromatogram?
The chromatography paper with the separated components.
What does Rf value equal to?
Dsub/Dsol
where Dsub is distance travelled by the substance,
and Dsol is distance travelled by the solvent.
