Reference no: EM132749321

Determine the hardness of the water prepared in Step 1. Answer must be given in mg of MgCO3 per liter of solution.

Data:

Mass of Epsom Salt: 0.78905 g

Mass of Sodium Carbonate: 5.3656 g

Mass of filter paper #1: 1.3140 g

Mass of filter paper #2: 1.3297 g

Mass of filter paper #3: 1.3091 g

Mass of watch glass #1: 35.6254 g

Mass of watch glass #2: 24.8519 g

Mass of watch glass #3: 24.7363 g

Mass of filter paper, watch glass, and precipitate #1: 37.0094

Mass of filter paper, watch glass, and precipitate #2: 26.2466

Mass of filter paper, watch glass, and precipitate #3: 26.1134

1. Why is it important to wet the filter paper first in Procedure step 7?
2. Why are only small quantities of rinse water used in Procedure step 8? (Hint: think about the time/efficiency of the procedure.)
3. This lab used a double replacement reaction to precipitate MgCO3. Would a single replacement reaction also be appropriate for this type of analysis? If yes, propose a balanced reaction. If no, justify your answer.
4. One lab group's procedure for this lab specified washing the precipitate with 25 ml of distilled water. Another lab group did not have a washing step specified. Would you expect any difference in the results between the two groups? Justify your answer.
5. If the amount of hardness in water was excessive, it could be possible to add insufficient sodium carbonate to precipitate all the magnesium ions present. Suggest an additional step or steps to your procedure to verify that all Mg+2 was precipitated from the hard water sample.