Intensive properties and extensive properties are types of physical properties of matter. The terms intensive and extensive were first described by physical chemist and physicist Richard C. Tolman in 1917. Here's a look at what intensive and extensive properties are, examples of them, and how to tell them apart.
Intensive Properties
Intensive properties are bulk properties, which means they do not depend on the amount of matter that is present. Examples of intensive properties include:
Boiling point
Density
State of matter
Color
Melting point
Odor
Temperature
Refractive Index
Luster
Hardness
Ductility
Malleability
Intensive properties can be used to help identify a sample because these characteristics do not depend on the amount of sample, nor do they change according to conditions.
Extensive Properties
Extensive properties do depend on the amount of matter that is present. An extensive property is considered additive for subsystems. Examples of extensive properties include:
Volume
Mass
Size
Weight
Length
The ratio between two extensive properties is an intensive property. For example, mass and volume are extensive properties, but their ratio (density) is an intensive property of matter.
While extensive properties are great for describing a sample, they aren't very helpful identifying it because they can change according to sample size or conditions.
Way to Tell Intensive and Extensive Properties Apart
One easy way to tell whether a physical property is intensive or extensive is to take two identical samples of a substance and put them together. If this doubles the property (e.g., twice the mass, twice as long), it's an extensive property. If the property is unchanged by altering the sample size, it's an intensive property.
Depends on what the measurement is.
She worked 30 hours per week.
The problem turns out to be the following:
2x+15=3x-15.
First you need to have only one x variable so you subtract the X's:
3x-2x=X
The problem now turns into 15=x-15.
You have to isolate the X so you do x+15. You have to do the same to the other side so 15+15=30, therefore x=30
