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secondary 3 | E Maths
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Rosie
Rosie

secondary 3 chevron_right E Maths chevron_right Singapore

help asap tysm

Date Posted: 1 year ago
Views: 267

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Arnold K H Tan
Arnold K H Tan's answer
2088 answers (A Helpful Person)
1st
Need to be more detailed with you answers... as you're doing Pure Chem.

Note impure substances melt/boil over a range of temperature. Easiest test for purity, if your sample size is large enough...

Must also know the advantages of chromatography. Eg: one big advantage is that only a small sample amount is required.
Rosie
Rosie
1 year ago
oh I see but for the test for purity how does dissolving it in a solvent be able to tell whether it’s pure?
Arnold K H Tan
Arnold K H Tan
1 year ago
It does not. If you use a different solvent that dissolves the substance + run a new chromatography experiment, you can then observe if the substance separates into 2 or more components (= impure) on the chromatogram, or remains a single component.
Rosie
Rosie
1 year ago
ohh I see so it’s basically retesting to see if it will move when dissolving in a different solvent
Arnold K H Tan
Arnold K H Tan
1 year ago
Yes... but of course... can always add a little in each solvent to test if the sample can actually dissolve, before using the solvent in a chromatography experiment.