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What is a pure substance
A pure substance is a single element/compound not mixed with any other substance
What is a formulation?
A mixture that has been designed as a useful product
What is chromatography used for?
To separate mixtures and help identify substances
What is the equation for Rf value
Rf= distance moved by substance/distance moved by solvent
How can we identify substances through chromatography?
Different compounds have differend Rf values so compounds with the same Rf values are the same
What is the test for hydrogen?
āsqueaky pop test'
ā³ Burning splint creates a pop sound if hydrogen is present
What is the test for oxygen?
Glowing splint
ā³ splint relights if oxygen is present
What is the test for carbon dioxide?
Lime water ā turns cloudy if carbon dioxide is present
What is the test for chlorine?
Damp litmus paper ā bleached and turns white
What colour flame does a lithium compound produce?
Crimson
What colour flame does a sodium compounds produce?
Yellow
What colour flame does a potassium compound produce?
Lilac
What colour flame does a copper compound produce?
Green
What colour flame does a calcium compound produce?
Orange-red
What happens if sodum hydroxide is added to calcium and magnesium?
white precipitate is produced
What happens when sodium hydroxide is added to aluminium?
Forms a white precipitate which dissolves when excess sodium hydroxide is added
what happens when sodium hydroxide is added to copper(II)?
A blue precipitate is formed
What happens when sodium hydroxide is added to Iron (II)?
A green precipitate is formed
What happens when sodium hydroxide is added to Iron (III)
A brown precipitate is formed
What is the test for carbonate (CO32-) ions?
Dilute acid ā bubbles are given off
ā³ test bubbles with limewater
What is the test for sulfate ions?
Add a few drops of dilute hydrochloric acid
Add a few drops of barium chloride solution
ā³ a white precipitate is formed if sulfate ions are present
Explain why, in a test for sulfate ions, the sample is acidified with hydrochloric acid first
Carbonate ions also produce a white precipitate with barium chloride solution
Acid reacts with any carbonate ions present and removes them
Which prevents a false negative
What is the test for halide ions?
Add a few drops of nitric acid
Add a few drops of dilute silver nitrate solution
What is formed when chloride ions react with silver nitrate?
A white precipitate
What is formed when bromide ions react with silver nitrate?
A cream precipitate
what is formed when iodide reacts with silver nitrate
A yellow precipitate
What are the advantages of using instrumental methods of anlysis?
Gives improved:
Speed
Accuracy
Sensitivity
Name 1 example of an instrumental method of analysis
Flame emission spectroscopy
How are metal ions and their concentrations identified using flame emission spectroscopy?
The sample is put into a flame
The light given out is passed through a spectroscope
This produces a line spectrum that can me analysed
Note 
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