What does a calorimetry experiment measure?

A calorimetry experiment specifically measures the heat absorbed or released during a chemical reaction or a physical change. This is achieved by observing the temperature change in a calorimeter, which is an insulated device that minimizes heat exchange with the environment.

In a typical calorimetry setup, when a reaction occurs, it either absorbs heat (endothermic reaction) or releases heat (exothermic reaction), which causes a change in temperature of the calorimeter. By measuring this temperature change and knowing the specific heat capacity of the substance involved, one can calculate the amount of heat exchanged during the process.

The other choices relate to different measurements that are not the primary focus of calorimetry. For instance, measuring the volume of gas produced during a reaction does not account for the thermal changes. Similarly, while knowing the mass of reactants and products is important in stoichiometry, it does not directly involve calorimetry as it does not indicate thermal changes. Lastly, measuring pH pertains to acidity or basicity and does not provide information about heat transfer, which is the central purpose of calorimetry. Understanding these distinctions helps clarify the unique role calorimetry plays in experimental chemistry.