Core Concepts
In this tutorial on physical versus chemical properties, you will learn about the differences between physical, chemical, intensive and extensive properties. We will also cover physical versus chemical changes.
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Physical vs Chemical Properties
Each property of matter can be classified as either extensive or intensive, and either a physical or a chemical property. Quantities such as mass and volume, that depend on the amount of matter present, are extensive properties. Other properties that that don’t rely on the amount of matter present, like color, are intensive properties. Extensive and intensive properties can be classified as a physical property because they can be measured without changing the substance’s unique chemical identity.
As an example, the freezing point of something is still considered a physical property. Picture water freezing or melting, when water changes temperature it is still water, just in a different state of matter. A chemical property is determined by a substances properties that become apparent during a chemical reaction.
Physical Properties
Physical properties can be measured or observed without changing the composition (chemical nature) of matter. Moreover, they can be further classified into intensive and extensive properties.
Some examples of a physical property include:
- color (intensive)
- density (intensive)
- volume (extensive)
- mass (extensive)
- boiling point (intensive): the temperature at which a substance boils
- melting point (intensive): the temperature at which a substance melts
Inside Physical vs Chemical Properties:
Intensive Properties
An intensive property is a property of matter that does not depend on the size or the amount of matter that is present. For example, melting point is an intensive physical property. No matter how much material you try and melt, the material must still reach the same melting temperature.
Extensive Properties
In contrast, an extensive property is a property of matter that does depend on the size or the amount of matter that is present. Therefore, it is considered additive. Mass is an extensive physical property. The mass of two objects together will be the sum of their individual masses.
Examples of physical properties, that are extensive properties:
- volume
- mass
- size
- weight
- length
Physical Changes
A physical change takes place without any changes in molecular composition. The same elemental composition is present throughout the change. For example, when water freezes into ice, the physical form of liquid water is changed; however, the constituent molecules stay the same. Things like cutting, tearing, grinding, and mixing are some more common types of a physical change. These processes change form, but not composition.
Chemical Properties
Chemical properties describe the ability of a substance to undergo chemical change or reaction to form new substances.
Examples of chemical properties:
- When a compound undergoes complete combustion (burning) with oxygen, it releases energy known as the heat of combustion.
- Chemical stability refers to whether a compound will react with water or air. Hydrolysis and oxidation are reactions that are both chemical properties.
- Flammability is a determination of whether or not a compound will burn when exposed to flame. Again, burning is a chemical reaction.
- The preferred oxidation state is the lowest-energy oxidation state that a metal will try to adopt, through reactions with other elements capable of accepting or donating electrons.
Chemical Changes
To identify a chemical property, we first need to look for a chemical change, consequently we will have identified a chemical property. A chemical change results in new matter of an undeniably different composition from the original matter. The atoms and/or compounds rearrange their structure, bonds break, and new bonds are made to form new compounds. For instance, burned wood becomes ash, carbon dioxide, and water, which are entirely new chemical compounds that did not exist prior to burning.
Physical vs chemical properties: Practice Problems
State whether each of the following is a physical or chemical property, or a physical or chemical change.
- Iron reacts with sulfur to give heat and flames.
- The density of potassium carbonate is 2.43 g/cm3.
- Dissolution of a salt in water.
- Mixing baking soda and vinegar produces bubbles.
- The melting point of aluminum is 660.3°C.
- HCl is a strong acid.
Solutions
- chemical change
- physical property
- chemical change
- chemical change
- physical property
- chemical property
Further Reading about physical vs chemical properties
It is really interesting to see everything applied to real life, we recommend this book to understand why in In biotechnology, pharmaceuticals, and the food and beverage sectors, the physical and chemical characteristics of food items are crucial!