Freezing point is the temperature at which a substance changes from a liquid to a solid. The freezing points of different substances vary greatly. Mercury, for example, freezes at -38.87 °C. However, gold has a freezing point of 1063 °C. The freezing point of any substance depends on the pressure pushing against the substance. Freezing points specified above are based on a pressure of 1 atmosphere (14.696 pounds per square inch [101.325 kilopascals]), the pressure of the atmosphere at average sea level.