Question

A substance can absorb or release heat energy by the process of

Answer 1

A substance can absorb heat energy in an endothermic process or release it in an exothermic process, which involves changes in enthalpy and are related to the heat capacity of the substance.

Step-by-step explanation:

A substance can absorb or release heat energy through the process of chemical reactions and physical changes. When heat is absorbed during these processes, it is known as an endothermic process. A common example of this is a chemical cold pack used in treating injuries, which absorbs heat to provide a cooling effect. Conversely, a process or reaction that releases heat is termed an exothermic process. The classic example of this is combustion, like the reaction in an oxyacetylene torch, where heat and light energy are emitted.

These processes are related to changes in enthalpy (H), which is the sum of a system's internal energy plus the product of its pressure and volume. For instance, melting and evaporating are endothermic as they need heat to overcome intermolecular forces; while freezing and condensation are exothermic as they release heat when intermolecular forces are reformed.

Heat capacity is another relevant concept in this context, which depends on the type and amount of substance and is considered an extensive property.

Answer 2

A substance can absorb or release heat energy by the process of radiation, convection, or conduction. Radiation refers to the transfer of energy through emission of electromagnetic waves or the movement of particles. An example of radiation is the Sun’s rays. This type of heat transfer does not require direct contact between objects. Convection, on the other hand, involves the hotter fluid rising while the colder fluid sinks. Convection occurs when you boil water in a pan. Lastly, conduction is a heat transfer that occurs as a result of temperature difference between two objects in contact. Heat is transferred from the hotter region to the colder region. Conduction occurs when ice melts in your hands.