Answer:
The enthalpy of a reaction can be measured using a Calorimeter.
Explanation:
Calorimetry--
It is a science or an act that is related to measuring the enthalpy change in a reaction i.e. it is used to measure the heat changes in a chemical reaction or physical changes.
The object or the apparatus that could be used for calomitery is known as a calorimeter.
Nowadays several scanning calorimeters are also used.
Hence, the answer is:
Calorimeter