Introduction

It is common to confuse the terms "physical change" and "chemical change", since both refer to transformations that materials can undergo. However, these transformations are very different from each other.

Physical change

A physical change is an alteration that substances undergo without their chemical composition being modified. That is, the substance remains the same, but it changes in its appearance, in its state of aggregation or on their properties physical. Examples of physical change are:

• Change of state: as when water goes from liquid to gas when boiling.
• Alteration of shape: such as when an object is cut or crushed.
• Change in texture or color: such as when you paint a wall or freeze food.

chemical change

A chemical change occurs when a chemical reaction occurs that changes the composition and structure of substances. That is, at the end of the process, products different from the original ones are obtained, with different physical and chemical properties. Some examples of chemical change are:

• Combustion: like when you burn paper or light a match.
• Decomposition: As when hydrogen peroxide decomposes into water and oxygen.
• Acid-base reaction: such as when hydrochloric acid is mixed with sodium hydroxide and sodium chloride and water are produced.

How to differentiate them?

To differentiate a physical change from a chemical one, we can observe some indicators:

Physical change:

• The substance does not change its chemical composition.
• The mass and number of atoms are conserved.
• No energy is generated or consumed.
• Breaking chemical bonds is not required.

chemical change:

• The substance changes its chemical composition.
• A change occurs in the mass and number of atoms.
• Energy is generated or consumed.
• It is required to break and/or form chemical bonds.

Conclusion

In summary, the difference between physical change and chemical change lies in the alteration that the substance undergoes and whether its chemical composition is modified or not. It is important to know this distinction to understand how materials react and to be able to predict the outcome of certain situations.

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