Sodium Pentahydration Lab Report

Data:
There were two separate sections of data collected: the Preparation Table(Table 1) and the Titration Table(Table 2). This was due to the initial production of the weight buret- the sodium thiosulfate solution and the dropping bottle- represented in Table 1 and the trials that occurred separately(Table 2). The initial mass of the solid sodium thiosulfate pentahydrate was 0.21 grams. Once the ten milliliters of water was added, the mass of the sodium thiosulfate solution as 9.70 grams(Table 1). In Table 2, the initial mass of the weight buret in trial one was 15.23 grams, the final mass of the buret was 14.14 grams. The second trial’s initial buret mass was also 14.14 grams, because no solution was used in between trials; however, the final mass was 13.04 grams.

This was approached by finding the molar mass of sodium thiosulfate pentahydrate and then using that value to convert the grams of the sodium thiosulfate used for the initial creation of the weigh bure into moles. The molar mass of sodium thiosulfate pentahydrate was found by adding the atomic masses of each element found in the compound, as shown in Example 1. The molar mass was then used to convert the grams used into moles by using dimensional analysis.
Example 1:
Na2S2O35H2O
(22.990Nag x 2)+(32.066Sg x 2)+(15.999Og x 3)+(1.008Hg x 10)+(15.999Og x 5)=
248.18 g/mol

Example 2:
0.21gx1 mol248.18 g=
8.46 x 10-4 mol

The last step in completing the Preparation Table was to calculate the concentration of the standard thiosulfate solution by dividing the moles of sodium thiosulfate pentahydrate by the mass of the solution, in grams(Example 3).
Example 3:
8.46 x 10-4 moles of Na2S2O35H2O/ 9.70 grams of solution = 8.72 x 10-5