Determining the Number of Moles of Water of...

INTRODUCTION Many salts that have been crystallized from water solutions appear to be perfectly dry, yet when heated they discharge large quantities of water. An example can be hydrated copper (II) sulfate. Exactly this salt is used in the described experiment. RESEARCH QUESTIONWhat is the number of moles of water of crystallization associated with one mole of copper (II) sulfate, in the hydrate CuSO4 * xH2O (s)? The independent variable in this experiment is sample thermal treatment ( heating and cooling) and the dependent variable is the number of moles of water of crystallization. A number of other variables can affect the final result of the experiment: whether the crucible was clean and dry before filling it with the salt, whether the†¦show more content†¦The observations were recorded.11.The place of work was cleaned up.Figure 1: Deployment of the burner, the support stand and the crucible, which should be followed, so that the sample may be heated properly.RESULTSDATA COLLECTION The row data, which was collected during the experiment, is shown in Table 1. Additional observations made during the experiment are listed in Table 2. Table 1 : Changes in mass of the crucible from the moment it was empty until it was reweighed after third cooling.Number of weightingsRecorded mass [g] (+/- 0.05g)Notes129.34Mass of empty crucible231.05Mass of crucible and hydrate before heating330.46Mass of crucible and hydrate after first heating430.44Mass of crucible and hydrate after second heating530.44Mass of crucible and hydrate after third heatingTable 2 : Observations made from the time the crucible was filled with the hydrated salt until the end of the third heating.Number of heatingsObservations0Crystals are blue, approximately as big as sugar crystals.1Crystals are bluish, they are smaller2Crystals are white, they are very small (they form a powder)3No visible changes ( still white powder )Figure 2: Observations made after adding a few drops of water to the an hydrous salt.DATA ANALYSIS1.Initial mass of the hydrated salt CuSO4 * xH2O (s) was calculated:mass of crucible and hydrate before heating - mass of empty crucible = mass of hydrate31.05 - 29.34=1.71 (g) (+/- 0.05g)2.The mass, and hence the