When a candle is lit, both chemical and physical changes occur during the burning process.
Chemical Change:
The primary chemical change involves the combustion of the candle wax, which is primarily made of hydrocarbons. When the candle wick is ignited, the heat melts the wax near the flame, turning it into liquid. This liquid wax is then drawn up the wick and vaporized by the heat of the flame. The vaporized wax reacts with oxygen in the air in a chemical reaction that produces carbon dioxide, water vapor, and heat. This reaction is a chemical change because it results in the formation of new substances (carbon dioxide and water) from the original substances (wax and oxygen). Additionally, this process releases energy in the form of light and heat.
Physical Change:
The physical change in a lit candle involves the melting of the solid wax. As the candle burns, the heat from the flame causes the solid wax near the wick to melt and transition into liquid wax. This is a physical change because it involves a change in the state of matter from solid to liquid without altering the chemical composition of the wax itself. When the candle is extinguished, the melted wax can solidify back into its original state upon cooling, demonstrating that it is a reversible physical change.
In summary, the chemical change is the combustion of wax leading to the production of new gases, while the physical change is the melting of solid wax into liquid wax.
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