Transcript Separating Mixtures

Separating Mixtures
Chapter 25
Decanting
Decanting means to pour
off. Decanting is used in
panning gold and in
pouring water off
vegetables.
Separating Solids from Liquids
• Filtration is the separation of small
insoluble solids from a liquid. e.g. sand
from water,Chalk from water
Evaporation
To purify Rock Salt(sand and
salt) using filtration and
evaporation.
Step (a) Crush rock salt with pestle and mortar.
Step (b) Add crushed rock to warm water.
Step (c) Heat water and stir thoroughly.
Step (d) Allow beaker to cool and filter the mixture.
Step (e) Heat the salt solution until it starts to “spit”.
Step (f) Continue heating the solution over a beaker of
boiling water until dry salt remains in the dish.
Distillation
• Distillation is the process involving the
vaporisation of a liquid by boiling it and
then condensing the liquid by cooling it.
• It can be used to separate a soluble solid
(e.g. Salt) from a liquid (e.g.seawater) to
give a pure sample of each.
Apparatus used to obtain a sample of pure water from
seawater(distillation)
Distillation can also be used to separate two
miscible liquids such as alcohol and water.
• It works on the basis that
alcohol boils at 78o C and
water boils at 100o C.
• The fractionating column
helps to give better
separation of the Alcohol
and the Water
Chromotography
• Chromatography is a method used to
separate a mixture of dissolved substances
in a solution.
As the solvent rises up the paper it carries some dyes
further up than others. This separates the various dyes
from the original sample.
Before
After
TextbookChapter24-Separating Mixtures A1.Physical.
A2.
A3.
A4.
A5.
A6.
A7.
A8.
A9.
A10.
A11.
Insoluble.
Soluble, solution.
Filtration, filter paper.
Salt, sugar, evaporation, crystals, clock glass.
78, 100, distillation, Liebig condenser.
Distillate.
Soluble, solution.
Distillation.
Chromatography, chromatography paper.
Soluble.
B1.
B2.
See Experiment 25.1, p.148.
See Experiment 25.3, p.148.
DiscoveringScience-TextbookSolutions28
B3.
(a) Distillation.
(b) Alcohol has a lower boiling point and there fore evaporates
quicker than water does. The alcohol vapour enters the inner
tube of the Liebig condenser, the walls of which are kept cold by
the water flowing in the outer sleeve of the condenser. This
condenses the alcohol vapour into alcohol liquid.
(c) So that the outer tube will fill completely with cold tap water.
B4. SeeExperiment24.3,p.146.
B5.
(a) A magnet.
(b) Saw dust would float and could be scooped off.
(c) Filtration followed by evaporation.
(d) Filtration.
(e) Evaporation, or distillation to save a sample of water.
(f) A magnet.
B6. (a)Sand (b)Ink. (c)Alcohol. (d)Copper sulfate.(e)Salt and water.
(f)Sand and water. (g)Alcohol and water.
B7. See Experiment 24.1, p.145.
B8. (a)Distillation.
(b)Alcohol and water.
(c)Liebig condenser.
(d)Filtration.
B9.(a)See Experiment 24.4,p.147.
(b)The mixture of coloured inks would separate out and end up at
different levels on the chromatography paper. A single coloured
ink would only leave one mark on the chromatography paper.
B10.
(a) (a) Liebig condenser. (b)Y. (c)Pure water, salt.
B11.(a)The ink spot moves upwards and the different colours in the ink
get separated out at different levels on the chromatography paper.
(b)The ink spot would move upwards and only one mark would be
left higher up on the chromatography paper.