Tests, Indicators and Reactions of Acids Flashcards
What colour flame does lithium produce?
Red
(Li+)
What colour flame does sodium produce?
Yellow
(Na+)
What colour flame does potassium produce?
Lilac
(K+)
What colour flame does calcium produce?
Orange-red
(Ca2+)
What colour flame does copper produce?
Blue-green
(Cu2+)
What type of wire do you need to test a cation?
Platinum wire
How do you clean the wire for a test?
Dip the platinum wire in HCl and then hold it in a flame. Once the loop burns without any colour change, dip it into the sample
How do you test for the ions in a metal hydroxide?
Add a few drops of NaOH to the metal hydroxide solution.
If you get a coloured insoluble hydroxide, you can tell which metal was in it
What colour would copper (II) hydroxide turn when added to NaOH?
Blue precipitate
Cu2+ + 2OH- -> Cu(OH)2
What colour would iron (II) hydroxide turn when added to NaOH?
Green
Fe2+ + 2OH- -> Fe(OH)2
What colour would iron (III) hydroxide turn when added to NaOH?
Reddish brown
Fe3+ + 3OH- -> Fe(OH)2
How can you test if there is ammonium ions in a substance?
Add some NaOH to a solution. If ammonia is given off, there are ammonium ions in the substance
What is the test for carbonates?
Add dilute HCL to the test sample
If carbonates are present, CO2 will be released
What is the test for sulfates?
Add dilute HCl, followed by barium chloride solution (BaCl2) to the solution
If a white precipitate forms (barium sulfate) the original compound was a sulfate
Why does HCl need to be added in the test for sulfates?
The HCl gets rid of any traces of carbonate or sulfite ions. Both of these would produce a precipitate, confusing the results
What is the test for halides?
Add dilute nitric acid and silver nitrate (AgNO3) solution
Why does HNO3 need to be added in the test for halides?
The HNO3 gets rid of carbonate or sulfite ions before the test
What happens when chloride ions are added to silver nitrate solution?
A white precipitate of silver chloride is formed
What happens when bromide ions are added to silver nitrate solution?
A cream precipitate of silver bromide is formed
What happens when iodide ions are added to silver nitrate solution?
A yellow precipitate of silver iodide is formed
What is the test for chlorine?
Damp blue litmus paper quickly turns red, then is immediately bleached white
What is the test for oxygen?
Glowing splint relights
What is the test for hydrogen?
Lit splint goes out with a squeaky pop
What is the test for carbon dioxide?
Limewater turns cloudy
