Calcium oxide is used in a self heating can . The diagram shows a self-heating can designed to raise the temperature of coffee to 60°C .
The button on the base of the can is pushed . The foil seperator breaks , allowing water to mix with the calcium oxide . After about 3 minutes , the can is opened by the ring pull . Insulating materials are used inside the walls of the can to prevent either of the lips or the fingers from being burned
1) Explain why the coffee becomes hot
2) suugest why it is nogt possible to re-use this self heating can