Reaction enthalpy measurement

What is the enthalpy of reaction?

The enthalpy of reaction (or heat of reaction) is the energy released or absorbed by a chemical reaction at constant temperature and pressure.

How to measure the enthalpy of reaction?

The reaction enthalpy is generally measured by so-called “batch” calorimetry. For this, a reaction mixture is first placed in a calorimetric cell whose temperature is regulated by the calorimetric oven. Then, the injection into the reactor of one of the reagents or of a catalyst makes it possible to start the reaction. The integration of the heat flux measured during the reaction makes it possible to calculate the reaction energy in joules (J). It can then be converted into J/g or J/mol depending on the quantities of reagent involved. The measurement also makes it possible to determine the duration of the reaction under the measurement conditions.

The enthalpy of reaction is often used to assess heating or cooling requirements for associated industrial processes. The heat capacity and density values ​​of the reaction mixtures are also quantities used for this purpose.

Mickaël Simond, CEO and Sales Director, Calnesis

Calnesis has several calorimeters allowing to carry out reactions under agitation, under inert or reactive gas, under pressure, etc.

Example of a thermogram obtained during a reaction enthalpy measurement. At time t=0, one of the reagents is added to the reaction mixture, which allows the start of the reaction (exothermic in this specific case). Integrating the signal until it returns to the baseline yields the total enthalpy of the reaction.

We can also reproduce the specific protocols of your processes, such as continuous injections or temperature ramps.