Unit 3 - Analysis (Testing For Positive And Negative Ions) Flashcards
What colour does lithium go in a flame?
Crimson
What colour does sodium go in a flame?
Yellow
What colour does potassium go in a flame?
Lilac
What colour does calcium go in a flame?
Red
What colour does barium go in a flame?
Green
When doing a flame test, how do you make sure the wire loop is completely clean?
By dipping in into hydrochloric acid and rinsing it with distilled water
What is the other test for metal ions?
Sodium hydroxide test - Add a few drops of sodium hydroxide solution to a solution of the unknown substance
What colour does the precipitate go for Calcium
White
What colour does the precipitate go for copper
Blue
What colour does the precipitate go for iron (II)?
Green
What colour does the precipitate go for iron (III)?
Brown
What colour does the precipitate go for aluminium?
White - at first
It then redissolves in excess NaOH to form a colourless solution
What colour does the precipitate go for magnesium?
White
Is the metal iron the positive or negative ion?
Positive
How can you test for metal ions?
Putting the substance in a flame
How do you test for carbonates?
Test for carbon dioxide - you can test to see if a gas is carbon dioxide by bubbling it through limewater
If it’s lime water: the limewater goes cloudy
You can use this test for carbonate ions since carbonates react with dilute acid to form carbon dioxide
How do you test for Halide ions? (Chloride, bromide and iodide)
Add dilute nitric acid followed by silver nitrate solution
Testing for negative ions: What precipitate does chloride give?
White Percipitate of Silver chloride
Testing for negative ions: what precipitate does bromide give
A cream ppte of silver bromide
Testing for negative ions: what ppte does iodide give
A yellow ppte of silver iodide
How do you test for sulfate ions? (
Add dilute HCL followed by barium chloride solution
Testing for negative ions: sulfate ions: what does a white ppte of barium sulfate mean?
The original compound was sulfate
Testing for negative ions: what result does carbonate give?
Effervescence
Testing for negative ions: what result does sulfate give?
White ppte
Testing for negative ions: what result does nitrate give?
Moist red litmus paper placed in the mouth of the tube turns blue