Determination of the Mass Percent of Sulfate in an Unknown Sulfate Salt

(Partner: Nina T.)


Procedure:


Day 1:
1) Measure 25ml of BaCl₂ in a graduated cylinder.
2) Measure half a spoonful of sulfate salt in a beaker. Determine the mass of the salt and the beaker.
3) Pour 5ml BaCl₂ into the beaker. 
4) Use a stirring rod to stir the solution.
5) Continue to pour BaCl₂ until it stops reacting with the salt. 
6) Take filter paper and measure. Record.
7) Put filter paper into a funnel and place a ring stand over your beaker. 
8) Slowly pour solution from Beaker 1 into the funnel placed over Beaker 2. 
9) Rinse through filter with distilled H₂O, leaving BaSO4.
10) Take filter paper and place in oven. 


Day 2:
11) Take filter paper out of oven and record mass. By subtracting the weight of the filter paper from the new mass, you get the mass of the BaSO4. 
12) Use stoichiometry to determine the theoretical mass of the SO4.
13) Calculate the mass percent of sulfate.


Observations:


BaCl_{2:
          Before: Clear liquid, transparent, like water
Sulfate Salt: 
          Before: White solid, like salt
BaCl 2 + Sulfate Salt:
          Solution: Foggy white, thick liquid}

BaSO4:
          After heating: white, smooth, cracked, like chalk

Day 1 Data		Day 2 Data
Mass	Grams	Mass	Grams
Empty 100ml beaker	29.73g	Filter Paper with BaSO4	1.42g
Beaker with Sulfate Salt	31.95g	(BaSO4)	(0.94g)
(Sulfate Salt in beaker)	(2.22g)
Filter Paper	0.48g

0.94g BaSO4	1 mol	1 SO4	96.06g SO4
	233.39g BaSO4	1 BaSO4	1 mol

= 0.39g SO₄


Mass % =     mass SO4         x 100 
                  mass sulfate salt

Mass % =     0.39g SO4         x 100  = 17.6% = mass percent of SO₄

                   2.22g sulfate salt

% Error =      17.6 - 55.1       x 100 = 68% = percent error
                          55.1