Intensive Properties of a system- density

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SUMMARY

Density is classified as an intensive property because it remains constant regardless of the amount of substance present, as long as the volume is kept constant. This means that when mass increases, volume also increases proportionally, resulting in a constant density value. The discussion clarifies that while both mass and volume are extensive properties, their ratio (density) is intensive. A practical way to understand this is by visualizing an object and considering whether its density changes when it is divided into smaller parts.

PREREQUISITES
  • Understanding of intensive and extensive properties in thermodynamics
  • Basic knowledge of mass and volume relationships
  • Familiarity with density calculations
  • Concept of ratio in mathematical terms
NEXT STEPS
  • Study the definitions and examples of intensive vs. extensive properties in thermodynamics
  • Learn about the implications of density in various materials and states of matter
  • Explore the mathematical derivation of density from mass and volume
  • Investigate real-world applications of density in engineering and material science
USEFUL FOR

This discussion is beneficial for students in physics or chemistry, educators teaching thermodynamics, and professionals in engineering or material science who need a clear understanding of the properties of materials.

leah3000
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How is density an intensive property?

If density= mass/ volume

wouldn't the density increase as the mass increases seeing that they are directly proportional?

I'm seeing this in my Uni lecture slides on thermodynamics; that density is an intensive property which means it is mass independent but I don't understand that. Is it an error? Or am I thinking of this in the wrong way?
 
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leah3000 said:
wouldn't the density increase as the mass increases seeing that they are directly proportional?

Only if you would be able to keep the volume constant.
 
Borek said:
Only if you would be able to keep the volume constant.

Ok so i understand that part, but won't the density still fluctuate more or less once the mass or volume is altered?

I guess I'm confused a bit because both mass and volume are extensive properties...so why is density intensive?
 
Usually if you take the ratio of two extensive quantities, you will get an intensive quantity. If you double the mass, you also double the volume so the factors of two cancel out when you take the ratio, and density remains the same.
 
I was taught to imagine the object and then cut it in half and ask yourself if that property has changed. Makes it pretty simple to see how a block of iron, for example, will have the same density as the two blocks you can make by cutting the original in half.

Its not a rigorous mathematical proof, but it helps clear things up when you're unsure.
 

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