Volume/volume and weight/weight persentages of the constituents in a composite

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To determine the volume/volume and weight/weight percentages of aluminum and lead in a composite material with a density of 8.3 g/m^3, one can use the known densities of aluminum and lead along with the average density of the composite. By setting the total volume to one cubic meter, two equations can be established: one for the total density and another for the total volume. These equations allow for solving the unknown volumes of aluminum and lead. The discussion highlights that knowing the total volume is not necessary, as density remains constant regardless of volume. Ultimately, this method provides a way to calculate the desired ratios without needing specific mass values.
mitnord
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Hi,

I have an aluminium/lead composite material with density of 8,3 g/m^3. How do I find volume/volume and weight/weight persentages of aluminium and lead in the material, if the masses of the composites are not given?

The volume of the material is also not known.

Thanks.
 
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You don't need to know the volume since the density is independent of volume.

8,3 grams per cubic metre sounds remarkably small for something involving metals!

You know Archimedes sorted this out for a king who wasn't sure that his crown was pure gold or alloyed with silver.

(DensityAl * VolumeAl) + (DensityPb * VolumePb) = (AverageDensity * TotalVolume)

VolumeAl + VolumePb = TotalVolume

Assume TotalVolume to be one cubic metre. You know the three densities (or you can look them up) so you've got two equations and two unknowns.

From that you can work out the ratios you are looking for.
 
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