individual molecules in that substance becomes forceful enough that the electrical forces holding them in place are overpowered The fixed structure then breaks up, leaving the molecules free to move from one place to another However, most of the molecules are still moving slowly enough that they remain influenced by the forces that once immobilized them, and so they remain loosely associated with each other They’re free to move, but move together This fluid but cohesive phase is a liquid Gases If the temperature continues to rise and the molecules move with a kinetic energy high enough that they can break away from each other’s influence completely and move freely into the air, the substance become a different kind of fluid, a gas The most familiar transition from the liquid phase to the gas phase is boiling, in which we transform liquid water into bubbles of water vapor, or steam Less obvious to the eye, because it’s so gradual, is the evaporation of water at temperatures below the boiling point The molecules in a liquid move with a wide range of kinetic energies, and a small portion of the molecules in room-temperature water are moving fast enough to escape from the surface and move into the air In fact, water molecules can even escape as a gas from solid ice! This direct transformation of a solid into a gas is called sublimation, and is the cause of that deterioration in foods known as “freezer burn,” in which crystalline water evaporates into the freezer’s cold, dry air Freeze-drying is a controlled version of the same process Many Food Molecules Can’t Change Phase Most of the molecules that the cook works ... a gas from solid ice! This direct transformation of a solid into a gas is called sublimation, and is the cause of that deterioration in foods known as “freezer burn,” in which crystalline water evaporates into the freezer’s cold, dry air... molecules in a liquid move with a wide range of kinetic energies, and a small portion of the molecules in room-temperature water are moving fast enough to escape from the surface and move into the air In fact, water molecules can even escape as... into the freezer’s cold, dry air Freeze-drying is a controlled version of the same process Many Food Molecules Can’t Change Phase Most of the molecules that the cook works