EVERYDAY SCIENCE

Detailed explanation-1: -A phase change is a physical process in which a substance goes from one phase to another. Usually the change occurs when adding or removing heat at a particular temperature, known as the melting point or the boiling point of the substance.

Detailed explanation-2: -Substances can change between the states of matter by adding or removing heat, also known as the transfer of thermal energy. Adding thermal energy causes a substance’s particles to move faster and farther apart; removing thermal energy causes a substance’s particles to move slower and closer together.

Detailed explanation-3: -During a phase change, matter changes from one phase to another, either through the addition of energy by heat and the transition to a more energetic state, or from the removal of energy by heat and the transition to a less energetic state.

Detailed explanation-4: -The energy that is changing during a phase change is potential energy. During a phase change, the heat added (PE increases) or released (PE decreases) will allow the molecules to move apart or come together. Heat absorbed causes the molecules to move farther apart by overcoming the intermolecular forces of attraction.

Detailed explanation-5: -All phase changes are accompanied by changes in the energy of a system. Changes from a more-ordered state to a less-ordered state (such as a liquid to a gas) are endothermic. Changes from a less-ordered state to a more-ordered state (such as a liquid to a solid) are always exothermic.