Percent Acetic Acid in Vinegar
Introduction: Acetic acid is reactive when combined with calcium carbonate. In this lab, we will use vinegar for its acetic acid and egg shells for their calcium carbonate. Marketable vinegar differs in its acetic acid concentration from 4-6%. Calcium carbonate reacts with the acetic acid in vinegar to produce carbon dioxide, water, and calcium acetate as represented by the equation: CaCO3 + 2HC2H3O2 CO2 + H2O + Ca(C2H3O2)2. The calcium carbonate reacts with the acetic acid in a 1:2 ratio. Therefore, for every one mole of calcium carbonate that reacts, 2 moles of acetic acid have reacted as well. Materials:
1. Broken eggshells
2. 2 125 mL flasks
3. Stirring rod
4. 25 mL vinegar
5. Filter paper
7. Electronic balance
8. Paper towels
9. Weighing paper
1. Put 25 mL of vinegar into the flask.
2. Weigh the dry eggshells using the electronic balance and the weighing paper. 3. Pour the eggshells into the vinegar. Stir this mixture around until it stops bubbling. To make this reaction happen faster, keep swirling the flask or use the stirring rod to crush the eggshells into even smaller pieces to increase the surface area. 4. Put the funnel in the other flask and put the filter paper in the funnel. 5. When the bubbles stop rising, filter the eggshells.
6. Dry the eggshells with a paper towel.
7. Retake the mass of the dry eggshells.
Mass of eggshells before reaction
Volume of vinegar used
Mass of dried egg shell after the reaction
Mass of eggshell (CaCO3) that reacted
1 - 0.5 = 0.5
Moles of calcium carbonate (CaCO3) that reacted
Ca: 40 0.5
C: 12 100g 100 =.005 moles
Molar ratio of CaCO3 to HC2H3O2 (acetic acid)
1CaCO3 + 2HC2H3O2 CO2 + H2O + Ca(C2H3O2)
1 : 2
Moles of HC2H3O2 that reacted
H: 4(1) .01
C: 2(12) 60g 60 ≈ .00017...
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