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Flashcards in Qualitative analysis Deck (12):

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