Physical changes occur when an object or substance undergoes a change in physical properties, such as texture, color, odor, weight, density or shape, while retaining the same chemical nature. A person can also observe these physical changes with no change to the object or substance's matter. There are several different types of physical changes an object can undergo.
Boiling is using heat to change a liquid to a gas. This occurs when a liquid reaches a temperature at which the vapor pressure equals the pressure of the gas above the liquid. When reaching the boiling point, the vapor bubbles up from the liquid.
Clouding occurs when a substance condenses from a gaseous state to a liquid state. Cloud formation in the sky is an example of clouding.
Dissolution, also referred to as dissolving, is the process of a solid or liquid forming a solution in a solvent.
Freezing, also referred to as solidification, is a physical change that occurs by withdrawing heat from a substance to change the substance from a liquid to a solid. The temperature must be below the substance's freezing point for the change to occur.
Freeze-drying, also referred to as lyophilization, lyophilisation and cryodesiccation, is a type of physical change in which a material or substance is frozen and warmed in a vacuum to reduce the surrounding pressure and allow the frozen water to sublime. Freeze-drying is useful for preserving perishable materials.
Frost, or icing, occurs when the surface of a solid cools below the freezing point of water and below the dew point of adjacent air.
Liquefaction is the process of converting a gas or solid into a liquid through condensation, melting or heating.
Melting, also referred to as fusion or thawing, occurs when the heat or pressure increases the internal heat of a solid to the melting point, resulting in the solid changing into a liquid.
Smoke is a hot vapor containing liquid particles, gases and carbonaceous matter from the air. Smoke occurs as the result of a combusted material mixing with the air. Smoke is also a by-product of fires.
Vaporization is a physical change in which a liquid or solid becomes a vapor or gas. The three different types of vaporization are boiling, evaporation and sublimation.