Core Concepts
In this tutorial on physical vs. chemical properties, you will learn about the differences between physical chemical, and intensive and extensive properties, as well as physical and 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. Things like mass and volume, that depend on the amount of matter that is being measured, are extensive properties. Things 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. It is used to identify a sample of matter because it does not change its property according to conditions. For example, melting point is a physical property, that is intensive.
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’s considered additive. They are not useful in identifying a sample of matter as their properties can change according to conditions. Mass is a physical property, that is extensive.
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 composition of an element or compound is present throughout the changes. For example, when water freezes into ice, the liquid state of water went through a physical change. 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. When those things happen they change form but mot 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 undergo reactions in order to achieve (if another element is present to accept or donate electrons).
Chemical Changes
To identify a chemical property, we first need to look for a chemical change, consequently we’ll have identified a chemical property. A chemical change results in new matter of an undeniably different composition from the original matter. The elements and/or compounds rearrange amonge or bonds break 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
- physical 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!