Separate Chemistry 2 - Ion tests Flashcards
Which tests test for metal ions?
- Flame test
- Hydroxide tests
What is the method for a flame test?
1) Clean the flame loop in acid
2) Place sample onto the loop
3) Place loop at the side of a roaring blue flame
4) Witness colour change
What are the results of different metals in a flame test?
Potassium (K+) --> Lilac flame Lithium (Li+) --> Red flame Sodium (Na+) --> Yellow flame Calcium (Ca2+) --> Orange flame Copper (Cu2+) --> Blue-green flame
How does a flame test work?
Excitation of outer electrons.
What is the method for a hydroxide test?
1) Dissolve the solid salt in distilled water
2) Add a few drops of sodium hydroxide
3) Record the colour of the precipitate
What are the results of different metals in a hydroxide test?
Iron II (Fe2+) --> Green Iron III (Fe3+) --> Brown Copper (Fe3+) --> Blue Calcium (Ca2+) --> White Aluminium (Al3+) --> White (dissolves with excess NaOH
How does the hydroxide test work?
Displacement reaction - sodium is more reactive and bonds to the hydroxide ions, leaving the metal precipitate.
What does the halide test, test for?
Halide ions.
Which tests test for non-metal ions?
- Halide test
- Carbonate test
- Sulphate test
- Ammonium test
What is the method for a halide test?
1) Dissolve the salt in distilled water
2) Add a few drops of nitric acid
3) Add a few drops of silver nitrate
4) Record the colour of the precipitate
What are the results of the different ions in a halide test?
Chloride (Cl-) –> White
Bromide (Br-) –> Cream
Iodine (I-) –> Yellow
How does a halide test work?
The silver reacts with the halide to form insoluble silver halides.
What is the method for a carbonate test?
1) Dissolve the solid in a few drops of acid
2) Observe for bubbles (gas production)
3) Bubble gas through limewater
What is the result of a carbonate test?
If carbon dioxide is being produced, the limewater will go cloudy.
What is the method for a sulphate test?
1) Dissolve the solid in distilled water
2) Add a few drops of hydrochloric acid
3) Add a few drops of barium chloride
