Good Science Victorian Curriculum Year 7
Digital sample of Matilda's newest publication, Good Science Victorian Curriculum Year, authored by Emma Craven and Aaron Elias. For more information visit www.matildaeducation.com.au or email Katrina Tucker, katrinatucker@matildaed.com.au
Digital sample of Matilda's newest publication, Good Science Victorian Curriculum Year, authored by Emma Craven and Aaron Elias. For more information visit www.matildaeducation.com.au or email Katrina Tucker, katrinatucker@matildaed.com.au
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CHEMICAL SCIENCES<br />
5.7<br />
SEPARATION<br />
TECHNIQUES:<br />
CHROMATO<br />
GRAPHY, CENTRI<br />
FUGATION<br />
AND FUNNEL<br />
SEPARATION<br />
LEARNING INTENTION<br />
At the end of this lesson I will be<br />
able to describe the processes<br />
of chromatography and<br />
centrifugation and suggest when<br />
these techniques should be used.<br />
KEY TERMS<br />
immiscible<br />
not able to be mixed<br />
1<br />
Different mixtures can be separated to find out more about<br />
their components or to use their components for different<br />
purposes. Forensic scientists sometimes use a process called<br />
chromatography to separate colours in inks and dyes to<br />
compare samples.<br />
Sometimes mixtures do not mix well together and so a<br />
separating funnel can be used to separate the components.<br />
Paper chromatography separates colours<br />
in mixtures<br />
Many inks and dyes are made of a mixture of different colours.<br />
Paper chromatography is a separating technique that uses a<br />
solvent, such as water, to separate the different colours.<br />
A spot of ink or dye is placed on a strip of paper that is touching<br />
a solvent, such as water or methylated spirits. As the solvent travels<br />
up the paper, it will dissolve the ink or dye. The more soluble the colour<br />
in the solvent, the further it is carried up the paper.<br />
Inks or dyes that are not very soluble don’t travel very far on the strip<br />
of paper. Dyes that are very soluble in water will travel further.<br />
The result is that the ink or dye mixture separates into its pure<br />
components, each of which will have a different colour.<br />
How can colours in inks or dyes be separated?<br />
paper chromatography<br />
a technique used to separate<br />
coloured substances using a<br />
strip of paper and a solvent<br />
LITERACY LINK<br />
READING<br />
Figure 5.14 Paper chromatography uses a strip<br />
of paper to separate an ink or dye spot.<br />
Wood or plastic<br />
Beaker<br />
Paper<br />
Colour separation<br />
of ink or dye<br />
Read section 1 out loud to a<br />
partner. They must come up with<br />
three questions about paper<br />
chromatography. Then swap<br />
roles and repeat for section 2.<br />
Spot of ink<br />
or dye<br />
Water<br />
Start<br />
Finish<br />
NUMERACY LINK<br />
UNITS<br />
A separating funnel contains<br />
150 mL of liquid. Convert 150 mL<br />
to litres.<br />
Formula: 1 mL = 0.001 L<br />
Figure 5.15 Forensic<br />
scientists can use<br />
chromatography to<br />
match pen and ink<br />
samples, or to compare<br />
dyes in fibre samples.<br />
80 GOOD SCIENCE VICTORIAN CURRICULUM 7
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