Conductometric and Gravimetric Determination

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0.301 g

0.220 g

Molarity of H2SO4

0.5

Molarity H2SO4 : 0.5 M

Graphs:

Trial 2

Trial 1

Analysis: In order to calculate the mass of the barium sulfate, we subtracted the mass of filter paper from the filter paper with the precipitate on it. Then by looking at the equivalence point we were able to see when the moles of the unknown and the moles of the solution are equal. We then used the titration method and gravimetric analysis to compare the molar amounts calculated and then compared which method was more precise. We found that titration is a better, but the calculations were not as close to the actual molar amount of barium sulfate. It is possible to determine the concentration of barium hydroxide using the equivalence point method though.

Actual Concentration: 0.3M

Calculations (Were from post lab question #2 and #4):

- 0.456M Ba(OH)2 and 0.564M Ba(OH)2

- .301 BaSO4 > 0.000129 mol BaSO4

- 0.22 BaSO4 > 00000946 mol BaSO4

Conclusion: If we use the reaction between sulfuric acid and barium hydroxide to determine the equivalence point, then we can determine the concentration of barium hydroxide. While our calculations using the titration results weren’t precise compared to the actual concentration of barium hydroxide. However they weren’t completely off and were much closer than our calculations using the method of gravimetric analysis.

Sources Of Error: One of the three sources of errors occurred when approximately 10 of the H2SO4 drops in our first trial were not measured by the drop counter therefore being missed calculated. The second source of error is human mistake, before we could collect the data for the weight of the precipitate, some of the precipitate had been touched thus lessening its quality. Lastly, the mixture was not stirred by the magnetic stirring rod for the first few minutes of the trial because we had forgotten to turn it on. In order to avoid these mistakes, testing the drop counter before starting our trials and making sure to begin to stir BEFORE adding the H2SO4 to the Ba(OH)2 will lessen these errors. Lastly, carefully handling the precipitate will make sure we don’t accidentally lose some or touch it.

Discussion Of Theory: The method of titration produces an equivalence point that occurs when the moles of the standard solution is equal to the moles of an unknown concentration. We used the equivalence point to determine the concentration of the unknown. Gravimetric analysis uses the process of drying a precipitate in order to measure it, which will supply different results compared to titration. If one solution has a known concentration, then the other can be calculated. In this experiment, volumetric analysis was more precise than gravimetric analysis.