Method for Dilution.
- Rinse the pipette with the solution.
- Pipette _cm^3 of this solution into a _cm^3 volumetric flask and make up to the mark using distilled water.
- Stopper and invert 3 times.
- Rinse the pipette with the diluted solution using a pipette filler.
- Transfer _cm^3 of the diluted solution to a conical flask using a pipette.
Carrying out a titration.
- Rinse out a pipette with the solution to go in the conical flask, transfer a known volume of the solution to a conical flask.
- Add 2 or 3 drops of indicator to the solution. (methyl orange or phenolphthalein-must be named)
- Rinse the burette with the solution of known concentration and fill up to the 0cm^3 line.
- Add the solution from the burette into the conical flask until the end point is reached. (state colour change)
- Repeat for accuracy.
Dip a nichrome wire into concentrated hydrochloric acid and then into the solid sample, hold at the edge of a blue bunsen flame. Record flame colour.
K+ - Lilac (pink through cobalt blue glass).
Na+ - Yellow/orange (give one)
Li+ - Crimson
Ca2+ - Brick red
Cu2+ - Blue-green
Ba2+ - Green
Testing for Halides
Acidify a solution of the salt using nitric acid and silver nitrate solution.
(Add dilute/concentrated ammonia solution to distinguish)
- Chloride ions will give a white precipitate which is soluble in dilute ammonia solution, and will dissolve to give a colourless solution.
- Bromide ions will give a cream precipitate which is insoluble in dilute ammonia solution but soluble in concentrated ammonia solution to give a colourless solution.
- Iodide ions will give a yellow precipitate which is insoluble in both dilute and concentrated ammonia solutions.