15. Compounds Elements
Two or more
DIFFERENT
elements
chemically
bonded together
Cannot be divided
into simpler
substances
Molecules of multiple
atoms of the same element
are NOT compounds
21. A method of separating a
mixture by carrying it in a
solution (or gas stream)
across an absorbent material.
22. ï Based on the principle
that different substances
dissolve at different rates
ï Used to separate
mixtures
ï Used to identify
unknown components
24. 1. Cut the filter paper so it does not touch
the sides of container
2. Draw a thin pencil line 1 cm from the
bottom
3. Transfer samples onto the filter paper on
top of the pencil line and mark clearly
4. Keep the samples at least 1 cm apart
25. 5. Fill a glass beaker up to about 1 cm with
a solvent
6. Attach the filter paper to a pencil and
immerse in solvent, so that liquid level
does not reach pencil line.
7. Compare analyte to controls for
identification of components, etc.
26. 1. Stationary phase absorbs the liquid
Liquid travels upwards
2. Liquid reaches samples
Samples dissolve and travel upwards
with liquid
3. Components are retained by stationary
phase to different extents
Separation
27. ï Pure substances have
unique boiling points
ï Impurities raises the
boiling point
ï Substances now boil over
a range of temperatures
depending on their
concentration
28. ï Pure substances have
unique melting points
ï Impurities lowers the
melting point
ï Substances now melt
over a range of
temperatures depending
on their concentration