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.