Final answer:
In a chemical reaction that releases energy, known as an exothermic reaction, energy is given off usually as heat, light, or sound, while adhering to the First Law of Thermodynamics and the law of conservation of energy.
Step-by-step explanation:
When a chemical reaction releases energy, it is known as an exothermic reaction. This type of reaction complies with the First Law of Thermodynamics, which states that energy in the universe is constant and cannot be created or destroyed, only transferred or transformed. A common example of an exothermic reaction is the combustion of methane in kitchen burners which releases heat energy.
During an exothermic reaction, the energy required to break chemical bonds in the reactants is less than the energy released when new bonds form in the products. This excess energy is often given off as heat, light, or sound. The law of conservation of energy ensures that the same amount of energy is present before and after the reaction, though its form has changed. This principle not only applies to heat and light but also to the energy stored within chemical bonds.
Biological systems, too, obey thermodynamic laws. For example, cellular respiration is an exothermic process where glucose is broken down, and the energy released is used to do work inside the cell or lost as heat. Similarly, in ecosystems, energy from sunlight is stored in plant molecules and later released by organisms that consume the plants. The First Law of Thermodynamics assures that all these processes, despite their complexity, adhere to the fundamental rule of energy conservation.