If I leave my bike outside the house for a long time, it rusts. Rust is a solid, dark brown substance produced when iron is exposed to the oxygen in the air. The formation of iron rust is a chemical change that begins with a substance having certain properties and ends with another substance that is completely different from the original material, as rust differs completely from iron and oxygen.

What is meant by chemical changes?

Chemical changes are usually referred to as chemical reactions, and they are accompanied by the absorption or production of energy in the form of heat, light, electricity, or sound.

Examples of chemical changes:

Cooking food changes the properties of the ingredients, including color and taste. Cooking causes a chemical change in the materials used to produce food. Gases are sometimes released from chemical changes; for example, carbon dioxide is released when vinegar is added to baking soda. We may have seen silver jewelry pieces that lost their shine and acquired a black layer; this is a chemical change resulting from the reaction of silver with oxygen in the air.

Evidence of chemical change:

If we look closely, we will find many clues to chemical changes around us. A change in color is one of the easily noticeable clues. Rust on iron and the loss of shine in silver are good examples of a color change. Other clues to chemical change include the observation of gas bubbles, the emission of an odor, or the sound of bubbling, such as the sound when an effervescent tablet is placed in water. Changes in the temperature of substances are also evidence of a chemical change; some materials may heat up due to chemical changes, while others may cool down. Another sign of chemical change is the emission of light; for example, burning is a chemical change accompanied by the release of heat and light.

Other examples of chemical changes:

- Mixing iron filings and sulfur. Iron is shiny silver and is attracted to a magnet, while sulfur is yellow powder.

- Heating a rod to a high temperature.

- When the two substances are mixed using the hot rod, a chemical change occurs, emitting light and heat.

- The resulting substance is iron sulfide, which is black and does not attract a magnet.

Conclusion:

Understanding chemical changes in our daily lives is crucial. Chemical reactions have a significant impact on the properties of materials, transforming them into new substances with different characteristics. By observing clues to chemical changes, such as color changes, gas release, thermal or light emission, we can understand and analyze many processes in our daily lives.

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