TOPIC 9 - Separate Chemistry 2 Flashcards
Colour of lithium ion flame
Red
Colour of sodium ion flame
Yellow
Potassium ion flame color
Lilac
Calcium ion flame
Orange-red
Copper ion flame color
Blue-green
Test for metal ions involving precipitate
Add sodium hydroxide solution to the solution and metal hydroxide may precipitate out of solution.
Aluminium precipitate color and ionic equation
White before redissolving in excess sodium hydroxide w colourless solution.
Al3+ + 3OH-»_space; Al(OH)3
Calcium precipitate color and ionic equation
White
Ca2+ + 2OH-»_space; Ca(OH)2
Copper precipitate color and ionic equation
Blue
Cu2+ + 2OH-»_space; Ca(OH)2
Iron(II) precipitate color and ionic equation
Green
Fe2+ + 2OH-»_space; Fe(OH)2
Iron(II) precipitate color and ionic equation
Brown
Fe3+ + 3OH-»_space; Fe(OH)3
How do you work out whether a substance contains ammonium ions?
Add sodium hydroxide solution and gently heat, ammonia gas will be given off.
How do you test for ammonia gas?
Hold a piece of damp red litmus paper over and ammonia gas will turn it blue.
How do you test for halide ions?
Add dilute nitric acid before a few drops of silver nitrate solution.
Chloride precipitate
When testing for anions
White precipitate of silver chloride
Bromide precipitate
When testing for anions
Cream precipitate of silver bromide
Iodide precipitate
When testing for anions
Yellow precipitate of silver iodide
How do you test for carbonate ions?
Symbol equation?
Add dilute acid and mixture will fizz as it will produce carbon dioxide gas.
CO32- + 2H+»_space; CO2 + H2O
How do you test for sulphate ions?
Add dilute hydrochloric acid before adding barium chloride solution, sulfate ions will produce a white precipitate of barium sulfate.
Flame photometry
Instrumental method allowing identification of ions in a dilute solution. Each ion produced a unique line spectrum.
Why is flame photometry better than flame tests on specific occasions?
As can identify ions within a mixture which flame tests can’t.
Advantages of using machines to analyse unknown substances
V sensitive
V fast
V accurate
Homologous series
A group of chemicals w similar chemical structures and functional group while sharing a trend in chemical properties.
Alkanes
Homologous series of hydrocarbons w general formula CnH2n+2. They are saturated.
Functional group
A group of atoms that determine how a molecule reacts.
Alkenes
Homologous series of hydrocarbons w a C=C functional group, unsaturated .
CnH2n