Phase transitions

Phase transitions play an important role in the study of Thermodynamics. The evaporation of a fluid or the melting of a solid, are examples of phase transitions. The phase of a given substance depends on the pressure and temperature. As an example of this water will boil at a lower temperature on the top of Everest than at sea level as there due to the differences in altitude there is a large pressure difference.

At ambient pressure and temperature, one would assume that the water in a glass would be in a liquid form. If we keep increasing the temperature of the water eventually it will boil, this is when the water will transition from the liquid phase to the gas phase. If you transfer the glass of water to the North Pole, most likely the water will transition from the liquid phase to solid phase as it freezes.