Answer ASAP

[VCE_2012]

For the following procedure what are the key things that need to be annotated within the diagram? (btw why is HCL added?)

1. Finely grind a small quantity of fertiliser using a motar and pestle. Accurately weight around 1.0g of the ground fertiliser in a 100ml beaker. Record the mass and the brand of fertiliser.

2. Add 50ml of distilled water and stir to dissolve as much of the fertiliser sample as possible. Filter the mixture into a 600ml beaker, washing the residue several times using distilled water

3. Add about 3ml of 2M hydrochloric acid to the filtrate and add more water so that the total volume is about 200ml. Boil the solution

4. Slowly add 15ml of 0.5M barium chloride solution from a burette to the hot solution. A white precipitate will form. Stir continuously.

5. Boil the mixture for a further minute. Remove it form the heat and allow the precipitate to settle. Ensure that no sulfate ions remain in the solution by adding several drops of barium chloride solution. If more precipitate forms, add a further 3ml of barium chloride solution and test again for unreacted sulfate ions.

6. Weigh in a clean, dry filter paper.

7. Place the filter paper in the funnel and collect the precipitate in the filter paper. use about 10ml of distilled water to wash any precipitate remaining in the beaker into the filter paper.

8. Collect the last drops of filtrate in a 100ml beaker and test for chloride ions by adding a few drops of silver nitrate solution to filtrate. If the solution becomes cloudy, wash the precipitate with a further 10ml of warm water and repeat the test

9. Allow filter paper and filtrated to dry

10. Weigh filter paper and filtrated and determine the mass of the residue.