By calculating the difference in the mass of the hydrate copper (II) sulfate and the anhydride we were able to determine the mass of water in the hydrate. This information was then used to determine the empirical formula of the hydrate, defined as a compound formed by the addition of water to another molecule. In the first trial, the mass of water in the hydrate was determined to be 0.41 g, while in the second trial the mass of water was 0.52 g. Moles of water associated with a single mole of anhydride were then calculated for both trials, giving the values of 4.7 and 4.5 moles of water, respectively. This indicated that the empirical formula of the hydrate might be copper (II) sulfate pentahydrate – CuSO4·5H2O.
Hydrates are chemical compounds that contain discrete water molecules as part of their crystalline structure. Water is bound in most hydrates in definite, stoichiometric proportions, and the number of water molecules bound per metal ion is often characteristic of a particular metal ion. Many hydrated salts can be transformed to the anhydrous (without water) compound by application of heat. In this experiment, we determine the empirical formula of copper (II) sulfate – CuSO4.
In this experiment, we used an electronic balance to weight a clean, dry crucible before obtaining a sample of copper (II) sulfate (CuSO4), bright blue crystals, from the instructor. We then weighted two samples for the first and second trial with the crucible and found the samples’ weight to be 1.19 g and 1.55 g, respectively. A Bunsen burner was then set up for the heating of the crucible, with a wire triangle on the iron ring ensuring that the wire triangle will hold the crucible in an upright position. After setting up the Bunsen burner we heated the crucible with copper (II) sulfate for around eight minutes. During the heating process we haven’t noticed any splattering or popping of the material. After the 8-minute...
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