Question

Is burning of candles a reversible or irreversible change? Is melting of wax a reversible or irreversible change?

Answer 1

If a change cannot be reversed, it is said to be irreversible. New materials are always generated during an irreversible transformation. These novel materials can be beneficial at times. Heating might result in an irreversible transformation. To cook a raw egg, for example, you heat it. It is not possible to convert a cooked egg back to a raw egg. A reversible change is one that can be reversed or undone. A reversible reaction is one in which the chemicals used to start the reaction may be recovered.

Complete Step By Step Answer:
When we light the candle, the wax in the vicinity of the wick melts. The liquid wax is absorbed by the wick. The heat created by the flame causes the liquid wax to evaporate. Burning is a chemical reaction that produces heat and light through oxidation. When a candle is burned in the open air, the mass of the product increases owing to ambient oxygen combining with the carbon and hydrogen in the candle wax to generate water vapor and carbon dioxide throughout the burning process. The reactants' characteristics are also changed. And it's an unstoppable shift. Because the burned candle thread cannot be recovered, candle burning is an irrevocable alteration.
Wax melts for a short time and then settles back into a solid state as it cools. As a result, the only change is physical, and the condition of matter shifts. Most substances are solid at low temperatures; as the temperature rises, they become liquid; and at even higher temperatures, they become gaseous. Melting is the transformation of a solid into a liquid. Wax melting is a transition of state from solid to liquid in and of itself. No new products are produced when a substance's physical state changes. The wax slowly melts and then freezes after a while (Physical change).

Note:
Chemical changes occur when a material combines with another to produce a new substance, a process known as chemical synthesis, or when a molecule decomposes into two or more distinct compounds, a process known as chemical decomposition. These processes are known as chemical reactions, and they are generally irreversible until they are followed by other chemical reactions. Some reactions create heat and are referred to as exothermic reactions, while others require heat to take place and are referred to as endothermic reactions. Chemical changes are an important element of the study of chemistry.