Why does the mouth get cold when eating ice cream

Why does the mouth get cold when eating ice cream  

Eating ice cream soon causes the mouth to get cold, possibly to the extent of making it feel quite uncomfortable. The mouth of a normal, healthy adult has a temperature of about 37 °C, and the ice cream has a maximum temperature of 0 °C, although it is likely to be in the range —5 to — 10°C if it recently came from the freezer. A large difference in temperature exists, so energy transfers from the mouth to the ice cream, causing it to melt. 

Ice cream melts as it warms in the mouth and surpasses its normal melting temperature see Chapter 5. 

The evidence for such a transfer of energy between the mouth and the ice cream is the change in temperature, itself a response to the minus-oneth law of thermodynamics (p. 7), which says heat travels from hot to cold. Furthermore, the zeroth law (p. 8) tells us energy will continue to transfer from the mouth (the hotter object) to the ice cream (the colder) until they are at the same temperature, i.e. when they are in thermal equilibrium. 

Absolutely everything possesses energy. We cannot see this energy directly, nor do we experience it except under certain conditions. It appears to be invisible because it is effectively locked within a species. We call the energy possessed by the object the internal energy , and give it the symbol U. 

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