Density vs Mass: Does Lower Density Mean Lighter?

[Notwen7]

Does lower density usually mean the material is lighter? I went through high school believing that an object with a larger molar mass is a larger object. However, doesn't a larger density mean that material in use is heavier since it have a more compact lattice structure?

 

[phyzguy]

Which is heavier, a penny (density = 9 g/cm^3) or a tank truck full of water (density = 1 g/cm^3)? Mass = density * volume, so the mass depends on the density and the size.

 

[Notwen7]

Sorry I should have been more clear. If you have two different chemicals in the same volume with different densities then the one with the highest density will be heavier.

Thank you for your help.

 

[Jorriss]

Sorry I should have been more clear. If you have two different chemicals in the same volume with different densities then the one with the highest density will be heavier.

Yes. Mass and weight are proportional to one another. If two objects are in basically the same location ie on earth, then whichever has the larger mass has a higher weight.

 

[LudusRex]

Density and mass are two different physical properties of a material. Density is defined as the amount of mass per unit volume, while mass is the amount of matter contained in an object. Therefore, lower density does not always mean lighter.

For example, a balloon filled with helium has a lower density than a balloon filled with air, but the helium balloon is still heavier because it has a larger mass. This is because even though the helium gas has a lower density, it occupies a larger volume than the air.

Similarly, a piece of styrofoam has a lower density than a piece of iron, but the iron is heavier because it has a larger mass. This is because the iron is more densely packed and has a higher molar mass.

In general, a material with a lower density may be lighter than a material with a higher density, but this is not always the case. The mass of an object depends on both its density and its volume. So, while a larger density may indicate a more compact lattice structure, it does not necessarily mean that the material is heavier.

It is important to keep in mind that density and mass are independent properties and cannot be used interchangeably. Therefore, it is not accurate to say that a larger molar mass always means a larger object, as there are many other factors that can affect the mass of an object.

In conclusion, while lower density may sometimes indicate a lighter material, it is not always the case. It is important to consider both density and mass when comparing the weight of different objects.