DETERMINATION OF THE CHEMICAL FORMULA FOR A HYDRATE USING MOLE RATIO OF WATER MASS AND MAGNESIUM SULPHATE
Ionic (salt) compounds are able to hold loose bonds with water molecules. A hydrate is a compound that incorporates water molecules into its crystalline lattice structure (McGraw-Hill Ryerson, 2014). Identifying a compound as hydrated or anhydrous is important as the mass of the compound increases if it contains water molecules. In nature, hydrates exist with a fixed ratio of water molecules bound to each formula unit. These salts are able to release water to become anhydrous, or the anhydrous compound can absorb water molecules into their ionic structures to become hydrated. (Crampton, 2014). The hydrated complex can easily become an anhydrous salt if the compound is heated causing the water to evaporate out of the compound. The mass of the water in the hydrate can be determined by subtracting the anhydrous complex from the hydrated complex. It is hypothesized that the chemical formula of a hydrate can be determined using the mass of the anhydrous salt compound and the mass of the evaporated water to identify the fixed mole ratio in which they exist. In this lab the chemical formula of hydrated magnesium sulphate is expressed as follows: MgSO4 xH2O
Table 1: Mass calculations of hydrated and anhydrous complex Calculation:
| Mass Calculation
Mass of hydrated complexMgSO4 xH2O
| Mass of hydrated complex, beaker and glass rod (subtract)Mass of beaker and glass rod
| 125.66g – 120.80g =
| Mass of anhydrous complex
| Mass of anhydrous complex, beaker and glass rod. (subtract)Mass of beaker and glass rod
| 123.56g – 120.80g =
Mass of hydrated complex – mass of anhydrous complex = water mass of compound 4.86g
Figure 1: Mass calculation of water (H2O) in the hydrated complex.
Table 2: Determining moles and mole ratio between magnesium sulphate and...
Cited: * Amundsen, L., & Landrø, M. (n.d.). GEO ExPro - Gas Hydrates - Part I: Burning Ice. GEO ExPro - Gas Hydrates - Part I: Burning Ice. Retrieved April 20, 2014, from http://www.geoexpro.com/articles/2012/12/gas-hydrates-part-i-burning-ice
* Clancy, C., Doram, T., Heimbecker, B., Mazza, M., McNulty, P., & Mustoe, F. (2010). Proportions in chemical compounds. McGraw-Hill Ryerson Chemistry 11 (p. 277). Toronto: McGraw-Hill Ryerson.
* Crampton, L. (n.d.). What is a Hydrate (Chemistry). HubPages. Retrieved April 20, 2014, from http://hubpages.com/hub/What-is-a-Hydrate-Chemistry
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