Difference between Physical and chemical change-Physical vs chemical change

written by Adeel Abbas

Physical changes will cause a pure substance to become denser or less dense, but they will not affect the number of atoms in the substance. Chemical changes involve reactions that can produce new substances with different properties from those of their reactants.

image showing example of physical change where ice cube is melting

Physical and chemical change are both forms of change that are caused by interactions within the system. Differences between physical and chemical changes are important to understand because they can have different effects on systems.

Physical Vs Chemical Change: What’s The Difference? 

The main difference between a Physical change and a chemical change is that physical change is the type of chemical change and chemical change happens when substances combine to form new substances having different properties.

A physical change occurs when heat or pressure causes a substance to become a different substance. Water, for example, can be heated until it turns into steam and then cooled again so that the steam condenses back into water droplets on the object being heated. The water has changed from its original state as liquid H2O to gas H2O vapor and back again!

In contrast, chemical changes happen when substances combine to form new substances with different properties. For example, hydrogen gas combined with oxygen gas creates an entirely new compound called water vapor (H2O). With these differences in mind, let’s explore how physical and chemical changes are similar and how they differ from each other.


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What is Physical change?

Physical change is relatively easy to define. Physical changes do not involve the rearrangement of particles, but rather are a result of some kind of external stimulus. Many things fit into this category including melting ice, evaporating water, and freezing cold air.

Physical changes happen when a material absorbs energy in the form of heat or light but does not change its state. An example is heating ice until it melts into water. The molecules in a solid are already moving around and bumping into each other constantly; this movement increases as heat is added to the system. However, even if all the particles were fixed in place (this can be done by cooling them down again), they would still be considered to have undergone a physical change from one phase to another because their internal kinetic energy has been changed due to an external influence – i.e., the addition of heat via your stovetop burner!

A physical change is reversible and does not produce a new product.

What is Chemical change?

A chemical reaction, on the other hand, requires that particles be rearranged. This might involve something as seemingly simple as burning wood to produce ash and smoke (the white stuff coming out of your fireplace), or it could result in a complex series of reactions like digestion!

When matter undergoes a chemical change, new products are formed because at least one product has been created from rearranging part(s) of the original reactant materials involved. A car battery begins with chemicals like zinc metal ions and sulfuric acid; when these two substances interact they create lead sulfate (PbSO₄) which will then become lead oxide (PbO).

The overall process happens very rapidly once the initial contact takes place. The energy required for this process to occur is called the activation energy, and it can be thought of as a “hump” or barrier that must be overcome in order for any reaction (chemical change) to happen at all!

A chemical change creates new products because particles are rearranged. Chemical reactions require an input of energy; however, unlike heat/light which only adds thermal kinetic energy into matter making it more excited, chemical reactions also add potential chemical bond energy into matter allowing elements within compounds to move around relative to one another so they may interact with other substances- converting them from solids, liquids or gases depending on the new energy requirements.

Chemical changes are not reversible and can be written as a chemical equation.

The primary difference between physical and chemical changes is that the former are reversible, while the latter usually aren’t. To learn more about this topic in detail, book a free class on themasterchemistry.com