Investigating The Mechanism Of Decomposition, Reaction Energetics, And Gas Evolution Of A Material

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Thermal analysis data is used to determine the mechanism of decomposition, reaction energetics, and gas evolution of a material, specifically calcium silicate, also called limestone. Based on the basic rules of thermodynamics, a hypothesis can be formed that, as limestone is heated, it decomposes into calcium oxide and carbon dioxide due to heat transfer and the creation of impurities. The addition of silicon oxide, or quartz, can also cause limestone to decompose in the same manner. This was tested using experiments including Thermogravimetric Analysis (TGA), Mass Spectrometry (MS), and Differential Scanning Calorimetry (DSC). Figures 1-3 confirm this hypothesis through extensive logging of data. Future work can include data
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Unlike pressure, temperature is a simple variable to alter. This is why it is preferred when analyzing controlled reaction rates, such as heat transfer. An increase in temperature causes certain materials, commonly salts, to decompose, controlling the free energy that is released. Salts, which are unstable at high temperatures, are ideal subjects for thermal analysis. For example, when CaCO3 decomposes into CaO and CO2, the nucleation of CaO causes a “decrease in temperature [that] represents the endothermic heat absorbed by the reaction.” The decomposition of a material is affected by various factors, such as the pressure exerted on the material while it is heated, the amount of time the material is exposed to heat, and the rate of heat transfer. (Kingery).

On a macroscopic level, as limestone is heated, it will darken in color as it separates into calcium oxide and carbon dioxide. As it decomposes, calcium oxide will be formed into a solid and carbon dioxide will be released as a gas. The calcined powder will retain its darker color, but would otherwise look similar to the initial limestone. Decomposition is a reaction to the impurities caused by the heating of the material. (Thermogravimetric).

Experimental Methods:
After collecting samples and placing the calcium silicate, limestone, into each machine for the duration of time needed to collect 230 data points, testing is completed. While in the
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