A self-heating survival ration container contains a compartment of food on top, and a separate reaction chamber at the base containing solid calcium oxide (CaOCaOCaO) and a breakable water pouch, as shown in the diagram.
When the button at the bottom of the container is pressed, the water pouch breaks and the water reacts with the calcium oxide.
Explain, in terms of heat energy transfer, why the food in the container becomes hot.
