number 9 and 10 DATE: 82 7 NAME DATA SHEET FOR PART B. UNKNOwN SAMPLE TRIAL 1 TR

Question

number 9 and 10

DATE: 82 7 NAME DATA SHEET FOR PART B. UNKNOwN SAMPLE TRIAL 1 TRAIL 2 1. Mass of the empty beaker and the watch glass 2. Mass of the beaker, watch glass, and the hydrate 3. Mass of the hydrate: 15 5112 (line 2) - (line 1) Goes 4. Mass of the anhydrous salt, beaker, and the watch glass after the first heating 5. Mass of the anhydrous salt, beaker, and the watch glass after the second heating 6. Mass of the anhydrous salt, beaker, and the watch glass after the third heating: 3 7. Mass of the water (line 2) - (line 6) 8. Percent of water in the hydrate: (line 7) / (line 3)] 100 9. Average percent of water in the hydrate 10. Identification of the unknown hydrate: (from the example in prelab question #2) Note: Possible hydrates are BaCl2.2H20, ZnS04.7H2O, and MgS04.7??.

Explanation / Answer

In experiment (Mass of Water/Mass of hydrate) = (1.9/2.31)= 0.605 -------------(1)

For each salt calculating (Mass of water/mass of hydrate ration)

1) BaCl2 . 2H2O = 2*18/(208.23+36)= 0.147----------------------------(2)

2) ZnSO4 . 7H2O = 7*18/(161.47+7*18) = 0.4383 - -------------------------(3)

3) MgSO4. 7H2O = 7*18/(120.36+7*18)= 0.512 ----------------------------------(4)

Comparing 1,2 ,3,4 we get salt is MgSO4. 7H2O.

P.S. (9) is average of trail 1 and trial 2 experiment.

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