Difference Between Physical and Chemical Properties

Measurable characteristics of matter may be categorized as either chemical or physical properties. What is the difference between a chemical property and a physical property? The answer has to do with chemical and physical changes of matter.

A Physical Property

A physical property is an aspect of matter that can be observed or measured without changing its chemical composition. Examples of physical properties include color, molecular weight, and volume.

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Chemical Properties and Physical Properties

By Anne Marie Helmenstine, Ph.D.

A Chemical Property

A chemical property may only be observed by changing the chemical identity of a substance. In other words, the only way to observe a chemical property is by performing a chemical reaction. This property measures the potential for undergoing a chemical change. Examples of chemical properties include reactivity, flammability and oxidation states.

Telling Physical and Chemical Properties Apart

Sometimes it can be tricky to know whether or not a chemical reaction has occurred. For example, when you melt ice into water, you can write the process in terms of a chemical reaction. However, the chemical formula on both sides of the reaction is the same. Since the chemical identity of the matter in question is unchanged, this process represents a physical change.

Thus melting point is a physical property. On the other hand, flammability is a chemical property of matter because the only way to know how readily a substance ignites is to burn it. In the chemical reaction for combustion, the reactants and products are different.

Look for Tell-Tale Signs of a Chemical Change

Usually, you don't have the chemical reaction for a process. You can look for tell-tale signs of a chemical change. These include bubbling, color change, temperature change, and precipitation formation. If you see signs of a chemical reaction, the characteristic you are measuring is most likely a chemical property. If these signs are absent, the characteristic is probably a physical property.