Qualitative analysis Flashcards
Name the flame tests and which colours they produce.
Calcium brick red
Sodium yellow
Potassium lilac
Copper green/blue
How to test for other cations not using the flame test
Add a few drops of sodium hydroxide a precipitation reaction can occur. The precipitate can tell which cation it is. Aluminium gives White precipitate Calcium gives white precipitate Copper gives pale blue precipitate Iron II gives green precipitate Iron III gives brown precipitate
What is a halide ion
A halogen atom with a negative charge
How can you identify different halide a ions?
Add silver nitrate and dilute nitric acid
Chloride gives a white precipitate
Bromide gives a cream precipitate
Iodide gives a yellow precipitate
How is water made safe
Chlorine is us dot kill bacteria
What makes water hard?
Minerals containing calcium and magnesium
Why does soap not work in hard water
Soap bubbles do not for. Quickly because the calcium and magnesium ions combine with the soap to make an insolvable precipitate.
How to remove hardness of water?
Temporary hardness can be removed by boiling. To remove permanent hardness you have to use an ion exchange column. The magnesium and calcium ions are replaced with sodium ions.
How to test for positive ions?
Add a few drops of sodium hydroxide NaOH, a precipitate will be formed the colour tells you which precipitate it is.
How to test for a sulfate so
Add dilute hydrochloric acid followed by barium chloride solution. A white precipitate of barium sulfate will be formed in a sulfate ion is present
Give to formulas to calculate moles and concentration
Mass in grams. Mass
—————– Concentration = ———-
RFM. Volume
Volume is always in dm3 so divide cm3 by 1000
What colours are the precipitates in positive ions
When sodium hydroxide is added Calcium gives white precipitate Copper gives blue Iron II gives green Iron III gives brown Aluminium gives white but then redissolves
