Why doesn't density depend on the amount of a substance?

Answer 1

For liquids and solids the short answer, at sort of normal pressures, is NO. Any weight of the same material weighs the same per unit volume. This is the definition of density. At extreme pressures like the bottom of the sea, normally incompressible liquids may have their molecules even more tightly packed and the liquid's density goes up.

For gases the rules aren't the same, when you put more gas into a sealed container, the pressure rises and the density goes up. Sea level air is more dense than air at 5 km for this reason - higher pressure. In addition, when you cool gases down, the gases contract and more mass fits into the same volume so the density goes up. Example: The hotter the air in a hot air balloon, the more lift it has. This is due to the reduced density of the hot air. The density of gases in reference materials is usually noted as being calculated at a Standard Temerature and Pressure (STP) to get around these variabiles.

Now lets get down to the atomic scale and look at the "more substance per volume" issue. The heavier the element the more mass in the form of protons and neutrons it has. So a cubic volume of each solid element will weigh more because there are more of these building blocks present. So at this leel the more "substance" the more weight per unit volume - higher density.

Answer 2

Density is an intensive property, which means it does not depend on the amount of a substance. It is defined as mass per unit volume, so as long as the composition of the substance remains the same, its density will also remain constant regardless of the amount.

Answer 3

density is mass divided by volume figure it out yourself

Answer 4

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Answer 5

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