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On a laboratory scale, sulfuric acid can be diluted by pouring concentrated acid onto crushed ice made from de-ionized water. The ice melts in an endothermic process while dissolving the acid. The amount of heat needed to melt the ice in this process is greater than the amount of heat evolved by dissolving the acid so the solution remains cold.
The reaction is named after Robert Bunsen. He did not discover the reaction, but he described it in detail in 1853. [3] A similar reaction is the basis for Karl Fischer titration. Note that at sufficiently high temperatures, concentrated H 2 SO 4 may react with HI, giving I 2, SO 2 and H 2 O, which reverses the reaction. [2]
The enthalpy change for this reaction is -57.62 kJ/mol at 25 °C. For weak acids or bases, the heat of neutralization is pH-dependent. [1] In the absence of any added mineral acid or alkali, some heat is required for complete dissociation. The total heat evolved during neutralization will be smaller.
The concept of neutralization is not limited to reactions in solution. For example, the reaction of limestone with acid such as sulfuric acid is also a neutralization reaction. [Ca,Mg]CO 3 (s) + H 2 SO 4 (aq) → (Ca 2+, Mg 2+)(aq) + SO 2− 4 (aq) + CO 2 (g) + H 2 O. Such reactions are important in soil chemistry.
For many substances, the formation reaction may be considered as the sum of a number of simpler reactions, either real or fictitious. The enthalpy of reaction can then be analyzed by applying Hess' law, which states that the sum of the enthalpy changes for a number of individual reaction steps equals the enthalpy change of the overall reaction.
Elimination reaction of cyclohexanol to cyclohexene with sulfuric acid and heat [1] An elimination reaction is a type of organic reaction in which two substituents are removed from a molecule in either a one- or two-step mechanism. [2] The one-step mechanism is known as the E2 reaction, and the two-step mechanism is known as the E1 reaction ...
For reactions which go rapidly to completion, it is often possible to measure the heat of reaction directly using a calorimeter. One large class of reactions for which such measurements are common is the combustion of organic compounds by reaction with molecular oxygen (O 2) to form carbon dioxide and water (H 2 O).
Because of that, sulfuric acid is sometimes concentrated to oleum for in-plant pipelines and then diluted back to acid for use in industrial reactions. In Richmond, California in 1993 a significant release occurred due to overheating, causing a release of sulfur trioxide [ 6 ] that absorbed moisture from the atmosphere, creating a mist of ...