Quicklime , hazards

Hazard Unslaked lime (quicklime) yields heat on mixing with water and is a caustic irritant. 

The exothermic reaction of quicklime with water and the rather small specific heats of both quicklime (0.946 J/g °C) and slaked lime (1.20 J/g °C) make it hazardous to store and transport lime in vessels made of wood. Wooden sailing ships carrying lime would occasionally catch fire when water leaked into the hold, (a) If a 500-g sample of water reacts with an equimolar amount of CaO (both at an initial temperature of 25 °C), what is the final temperature of the product, Ca(OH)2 Assume that the product absorbs all of the heat released in the reaction, (b) Given that the standard enthalpies of formation of CaO and H2O are —635.6 kJ/mol and —285.8 kJ/mol, respectively, calculate the standard enthalpy of formation of Ca(OH)2. 

Considerable interest was generated in 1990/91 by reports arising from the US Environmental Protection Agency stating that the use of quicklime to stabilise PCB-contaminated soil had (apparently) led to the disappearance of the PCBs. However, it subsequently appeared likely that the PCBs had not been destroyed [32.38]. Indeed, the suggestion was made that, if quicklime were able to replace chlorine atoms in PCBs by hydroxyl groups, the reaction products might be more hazardous than the PCBs [32.39]. 

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