Specific Properties of Matter Name: Erin Status: student Grade: 9-12 Location: NJ Country: USA Question: What exactly is "specific" property of matter? Would density be considered one because it is not always constant? Replies: A 'specific' property is a property that depends on or is calculated based on another measurable property. You give an example of density; density is considered 'specific' because it can be calculated from volume and mass. Some other good examples are: - specific gravity - the density of a material relative to the density of water (volume and mass of the object, known density of water) - specific heat - the amount of energy required to raise a specific mass by a specified number of degrees of temperature (temperature, heat input, mass) - 'g-force'- acceleration relative to earth's gravity (acceleration, known acceleration due to gravity on earth) -- and thanks to Wikipedia for reminding of that one! Often, specific properties are a ratio of two measurements with identical units. Specific gravity, for example, is a ratio of one density to another. When performing calculations, specific units are easier because they are 'dimensionless' (they do not have units). It's also easier to think about certain properties relative to a commonly known property. Like how dense something is in terms of water instead of having to figure out of 60 pounds per cubic foot is going to float or not... Hope this helps! Burr Zimmerman Erin, If I understand your question correctly, you are looking for properties that all matter have. The first thing that comes to mind is "mass". Since mass is a measure of the amount of matter, then this is something that all matter have. Greg (Roberto Gregorius) I have never seen a precise definition of a "specific" property. The only properties I can think of that are called "specific" are specific heat and specific gravity. Both of these are intrinsic quantities, that is, they are a property of the material itself, and do not depend on how much material is present. For example, density, which is the mass of a sample of a substance divided by its volume, is an intrinsic property. No matter how much of the stuff you have, changing the amount does not automatically change the density. By contrast, mass is an extrinsic property. Doubling the amount of stuff doubles the mass. Although density is not necessarily constant, it does not depend in particular on how mu7ch stuff you have. Rather, it depends on pressure, temperature, and crystalline form (for solids). Increasing the amount of stuff does not necessarily change the density; sure, if you cram twice the amount of stuff into the same volume, you are increasing the density, but in doing so you need to change the some other quantity as well. I do not know if this is general, but the two "specific" properties mentioned above are actually pure, unitless ratios as well as being intrinsic. "Specific gravity" is the density of a substance divided by the density of water. By the same token, "specific heat" is the intrinsic heat capacity of a substance divided by the intrinsic heat capacity of water. Richard Barrans, Ph.D., M.Ed. Department of Physics and Astronomy The term "specific" does not have a well defined chemical meaning. There are terms like "specific" gravity, and "specific" heat. A common meaning (but by no means "cast in stone") is that the term "specific" (whatever) refers to the value of some property per gram of material. Vince Calder Click here to return to the Material Science Archives

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