Lab Report E5 PDF

Preview

Summary

lab report...

Description

Nephtalie Delva 2/04/22 Experiment 5: Percent Water in a Hydrated Salt

In this experiment, the percent by mass of water in a hydrated salt will be determined. Also, we will learn how to use lab apparatus.

Hypothesis: If we heat a sample of hydrated salt, then the mass of the salt will decrease since water molecules escaped the ion.

Procedures: 1- heat the crucible for about 5 minutes with high temperatures. Allow them to slowly cools them and measures the mass of the crucible and the lid separately. Record the data. 2- Add about 0.5 g (±0.001) of the hydrated salt into the crucible then collect the data. 3- Return the crucible with the salt inside to the holding tray (with tongs) and place the lid slightly off the crucible to allow the water molecules to escape. Gradually intensify the heat for about 5 minutes then measure the mass of the crucible with the dried salt. 4- Reheat the sample for 2 minutes then measure the mass again. Repeat this step 2 more

times to make sure that all water molecules have escaped successfully. 5- Repeat the experiment with 2 more samples of the same salt for a total of three trials then

Discussion: In this experiment, we calculated the percent of water in a hydrated salt. We were able to perform this experiment by determining the mass of the hydrated salt before and after heating the sample multiple times. The difference in the masses is the amount of water that was released. The percent mass of the escaped water was then divided by the initial mass of the sample and multiplied by 100. For this experiment we resulted in an average of 54.86% H2O in the sample of hydrated salt. The relative standard deviation of %H2O in the sample was 5.54%. Therefore, we are confident that our unknown sample should be MgSO4 x 7H2O because the percent of water in magnesium sulfate hexahydrate is 51.2%. With an average of 54.86% and a standard deviation of 3.0406, we can confidently say these measurements correspond to our hydrated salt sample. Our calculations are in reasonable range to consider it close enough to justify that or sample was in fact the MgSO4 x 7H2O. These results were expected because since we followed the procedures carefully, we should’ve gotten an accurate percentage of the water that matches the unknown sample.

Conclusion: In this lab we discovered the identity of an unknown sample of hydrated salt by

calculating the %H2O in the ion. According to our final average of %H2O (54.86%), our results were consistent with the accurate %H2O in a sample of MgSO4 x 7H2O provided by our professor which was 51.2%. We can conclude that our results also support our initial hypothesis: If we heat a sample of hydrated salt, then the mass of the salt will decrease since water molecules escaped the ion....