is the reversible physical change that occurs when a substance, such as water, changes from one state of matter to another Share specific characteristics related to energy and temperature. The temperature of a substance does not change. Energy is either absorbed or released.
melting, freezing, vaporization, condensation, sublimation, and deposition are six common phase changes . all of these phase changes share certain characteristics related to energy and temperature
temperature and phase changes
the temperature of a substance does not change during a phase change
the temperature of the substance does not change during a phase change but can change before and after
energy and phase change
energy is either absorbed or released during a phase change
(endothermic change, heat of fusion, exothermic change)
the system absorbs energy from its surroundings (such as melting/hot)
heat of fusion
the amount of energy absorbed by melting. it varies for each substance
the system releases energy to its surroundings (such as freezing/cold)
melting and freezing
the arrangement of moleucules in water becomes less orderly as water melts and more orderly as water freezes
water molecules are in fixed positions. when the ice is removed from the freezer the heat in the air flows through the ice. as the ice gains energy the molecules vibrate more quickly at the 0 degree temperature the molecules may have enough energy to overcome the attractions and move from their fixed proportions when all the molecules are able to move the melting is complete. any energy gained by the water after the phase change increases the average kinetic energy of the molecules, and the temperature rises.
as the average kinetic energy of the molecules decreases the movement slow down the temperature at the freezing point they may move so slowly that they create an attraction and
an energy measurement
the phase change where a substance changes from a liquid to a gas. it is endothermic. two processes- boiling and evaporation
heat of vaporization
the amount of energy a substance absorbs when it vaporizes. it varies between substances.
the process that changes a substance from a liquid to a gas at temperatures below its boiling point. the greater the surface area of the substance, the faster it evaporates. this happens on the surface of the substance.
the gaseous phase of a substance that is normally a solid or liquid at room temperature.
the pressure caused by the collisions of the vapor and the walls of the container. it increases as the temperature increases.
the phase change when a substance changes from a gas or vapor to a liquid. it is a exothermic process.
the phase change when a substance changes from a solid to a gas or vapor without changing into a liquid first. it is an endothermic change.
when a gas or vapor directly changes into a solid without becoming a liquid first. it is an exothermic change. it is the reverse of sublimation.