C8 Chemical analysis
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What is a pure substance?
a substance with only 1 element/compound throughout
How can we test how pure a substance is?
we can compare MP/BP and the closer to the actual value, the purer it it.
What is the effect of impurities on the melting point?
impurities lower the melting point
What is the effect of impurities on the boiling point?
impurities increase the boiling point of a sample
what are formulations?
useful mixtures made of exact amounts of components
What is in the formulation of paint?
pigment solvent binder additives
Why are formulations useful in the pharmacutical industry?
so chemists can ensure drugs are delivered to the correct part of the body, at the right concentration and has a long shelf life
What is chromatography?
a method to seperate the substances of a mixture
what are the 2 phases in chromatography?
a mobile phase a stationary phase
how do you calculate the Rf value from chromatography?
distance travelled by solvent
What has to be done to make chromatography useful?
test a pure substance next to it so you can compare
What is the test for chlorine?
bleeches damp litmus paper white
What is the test for oxygen?
ignites a glowing splint
What is the test for carbon dioxide?
turns lime water (calcium hydroxide) cloudy
What si the test for hydrogen?
makes a squeaky pop when ignited with a lit splint
What are the 3 test for anions?
dilute acid-to test for carbonates barium chloride and HCL- can test for sulphates nitric acid and silver nitrate can test for halides
How can you test for carbonates?
add dilute acid and see if it turns limewater cloudy as co2 is released
How can you test for sulfates?
add a few drops on HCL and a few drops of barium chloride. a white precipitate will form if sulfate ions are present
How can you test for halides
add a few drops of nitric acid and silver nitrate. the colour of precipitate determines the halide ion
In a halide ion test, what precipitates do chloride ions form?
white
In a halide ion test, what precipitates do bromide ions form?
cream
In a halide ion test, what precipitates do iodide ions form?
yellow
What colour flame to lithium ions burn with?
crimson
What colour flame to sodium ions burn with?
yellow