Chemical analysis Flashcards
What metals are tested in flame tests
Lithium, Sodium, Potassium, Calcium and Copper
How do you test for iron
Add a few drops of Sodium Hydroxide to a test tube with substance
For Iron (II) there is a green precipitate
For Iron(III) there is a brown precipitate
Describe a test for ammonium ions
-Add sodium hydroxide
-Test gas with damp red litmus paper
-The red litmus paper turns blue if present
Describe a physical test for pure water
-Measure the boiling point of the water
-It is pure if it’s boiling point is 100C
Describe a test for Chlorine Gas
-Use damp blue litmus paper
-If chlorine is present it goes red and bleached.
Colour of universal indicator when added to product of Lithium + water
Blue/Purple because hydroxide ions are present
Why does the wire need to be cleaned before a flame test?
-To remove any substances left on the wire so the colour of the flame isn’t affected.
Test for sulfate ions
-Add dilute hydrochloric acid
-Add barium chloride
-White precipitate is present
Test for presence of water (Not the pure test)
-Add anhydrous copper (ii) sulfate and if water is present the white powder turns blue.
Test for chloride ions
-Add nitric acid
-Add silver nitrate solution
-White precipitate forms
Test for carbonate
-Add acid
-Bubble gas formed through limewater
-Turns cloudy then it is a carbonate
State one chemical property of the product of combustion that classifies magnesium as a metal
Magnesium oxide is basic.
Colour results for flame tests
Lithium - Red
Sodium - Yellow
Potassium - Lilac
Calcium - Orange-red
Copper - Blue-green.
What is the Colour change when Ethanol is oxidized to form ethanoic acid
Orange to Green.
