Cement, the binder used to hold objects together, most commonly used in concrete and mortar. The chemistry of cement can be thought of as a deconstruction of a chemical, only to reconstruct the same chemical, but in a different shape. This molecule that we will be looking at is Calcium Carbonate, a component of seashells, and limestone. To start the process of creating cement, the CaCO3 must be broken down into Calcium oxide through heating it at 825°C, in a process called lime calcination, possessing the equation CaCO3 → CaO + CO2. This Calcium oxide exists in a light powdery form, capable of being transported easily to wherever needs to be cemented. Once the cement is ready to be made, the CaO is mixed with water to produce Calcium Hydroxide, Ca(OH)2, in the equation CaO + H2O → Ca(OH)2. This watery paste is ready to be placed into the mould to set. In the setting process, the Calcium Hydroxide returns to it's original state of Calcium Carbonate, through a slow process of combining with the carbon dioxide within the air in the chemical equation Ca(OH)2 + CO2 → CaCO3 + H2O.
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