How hard is sea water

 To measure the hardness of sea water we :

- Fill a burette with 0,01 M EDTA.
- Add 10 mL of sea water with a 10 mL pipette and a bulb, to a 250mL erlenmeyer flask, along with 20mL of the ammoniac buffer and 6-8 drops of eriochrome Black T indicator.
- Swirl
-Put a burette above the flask, filling it with EDTA and turn the stopcock to add solution drop by drop. When it's blue, close the stopcock.
-Calculate the equivalent mL of calcium carbonate per L.
 

Florian.C ~ Tina.L