RP4: Identification of cations and anions Flashcards
1
Q
How do you test for group 2 metal cations?
A
- Place 10 drops of a group 2 compound in a test tube (0.1moldm-3)
- Add 10 drops of 0.6 moldm-3 NaOH to test tube. Record any observations.
- Continue to add NaOH so it is in excess. Record any observations.
- Repeat with other group 2 compounds.
2
Q
How would you distinguish between calcium bromide and strontium chloride?
A
- Place 10 drops of BaCl2 in a test tube.
- Add 10 drops of sulfuric acid and record observations.
- Continue to add sulfuric acid until in excess. Record observations.
- Repeat for other the group 2 compounds.
3
Q
How do you test for ammonium ions?
A
- Place 10 drops of NH4Cl into a test tube.
- Add 10 drops of NaOH solution. Shake.
- Warm the solution in the test tube.
- Test the gas released with damp red litmus paper.
- It if goes blue, ammonium ions are present.
4
Q
How do you test for Group 7 ions?
A
- Add nitric acid and silver nitrate. Record observations.
2. To samples of this solution,, add dilute and then concentrated ammonia.
5
Q
How do you test hydroxide ions?
A
- Test a 1cm depth of solution in a test tube with red litmus paper or universal indicator.
- Record your observations.
- Sodium hydroxide will turn damp red litmus paper blue.
6
Q
How do you test for carbonate ions?
A
- Put 2cm3 of Calcium Hydroxide into a test tube.
- Add 3cm2 of Sodium Carbonate into another test tube then add an equal volume of dilute HCl.
- Immediately put in delivery tube with open end into the Calcium Hydroxide test tube.
- If Calcium Hydroxide goes cloudy, carbonate ions were present in the other test tube.
7
Q
How do you test for Sulfate ions?
A
Add HCl and BaCl2 to the suspected Sulfate solution.
Sulfate ions present = white precipitate of BaSO4 will form
8
Q
What is the order of testing ions?
A
Carbonate, Sulfate, Halide
Prevents false positive results occurring.
