Which describes how chemical changes are different from physical changes
Well, chemical changes are like my jokes - they're a real reaction. Physical changes, on the other hand, are more like a costume change - just a superficial alteration. So basically, chemical changes involve a transformation in the composition of substances, while physical changes only affect their appearance or state of matter. It's like turning a marshmallow into crispy s'mores - that's a chemical change. But if you simply melt the marshmallow, it's just a physical change, because it's still the same gooey deliciousness, just in a different form!
Chemical changes are different from physical changes in several ways. Here are the main differences:
1. Composition: In a chemical change, the composition of the substance(s) involved is altered, resulting in the formation of new substances with different chemical properties. In contrast, physical changes do not result in a change in composition. The same substance(s) are present before and after a physical change; only their physical state or appearance may be altered.
2. Irreversibility: Chemical changes are often irreversible, meaning that it is generally not possible to revert the new substances back to the original ones. Once a chemical reaction has occurred, it usually cannot be undone. On the other hand, most physical changes are reversible, allowing the substances to return to their original state once the external conditions change back.
3. Energy changes: Chemical changes often involve energy changes, such as the absorption or release of heat, light, or sound. These energy changes are often indicative of a chemical reaction taking place. In physical changes, there may be energy changes as well, but they are usually less dramatic and not directly related to the transformation of substances.
4. Activation energy: Chemical changes typically require an input of energy in the form of activation energy to begin the reaction. Activation energy is the minimum amount of energy needed for a chemical reaction to occur. Physical changes, on the other hand, do not require activation energy to take place. They can occur spontaneously based on changes in temperature, pressure, or other physical conditions.
5. Properties: Chemical changes result in the formation of new substances with different properties, such as changes in color, odor, taste, or reactivity. Physical changes, on the other hand, do not alter the fundamental properties of a substance. They may only affect its physical appearance (such as changing state from solid to liquid) or other physical characteristics (such as changing shape).
Chemical changes and physical changes are two different types of transformations that can occur in matter. Here's a breakdown explaining how they differ:
1. Nature of Change:
- Chemical Change: A chemical change involves a rearrangement of the atoms and the formation of new substances with different chemical properties. The original substances are converted into entirely different substances. Examples of chemical changes include burning a piece of paper or rusting of iron.
- Physical Change: A physical change, on the other hand, does not alter the chemical composition of a substance. It involves changes in the physical state, size, shape, or phase of matter, without forming new substances. Examples of physical changes include melting ice into water or cutting a piece of wood into smaller pieces.
2. Reversibility:
- Chemical Change: Chemical changes are often irreversible. Once a chemical change occurs, it is challenging or impossible to reverse it and revert to the original substances.
- Physical Change: Physical changes are mostly reversible. In most cases, if the conditions are restored to their initial state, the original properties of the substance can be regained.
3. Energy Changes:
- Chemical Change: Chemical changes typically involve the absorption or release of energy in the form of heat, light, or sound. The energy changes during a chemical reaction are often more significant compared to physical changes.
- Physical Change: Physical changes involve a transfer of energy, but the energy changes may not be as significant as in chemical changes. For example, energy is absorbed or released during the phase change of a substance (e.g., melting or boiling).
In summary, chemical changes involve the formation of new substances with different properties, are often irreversible, and usually involve significant energy changes. Physical changes, on the other hand, do not modify the chemical composition, are often reversible, and generally have less significant energy changes.
From Google:
The difference between a physical reaction and a chemical reaction is composition. In a chemical reaction, there is a change in the composition of the substances in question; in a physical change there is a difference in the appearance, smell, or simple display of a sample of matter without a change in composition.