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Calculate a value for the Avogadro constant

I got this dodgy question:

Crystals of metallic copper have a cubic unit cell which contains four copper atoms. By X-ray diffraction, the length of the side of this cubic unit cell is found to be 3.61x10-10m. The density of copper is 8.920g cm-3 and its relative atomic mass is 63.5. Use this information to calculate a value for the Avogadro constant, L.

Any help is much appreciated :smile:

Reply 1

Zygroth

1 mole = 63.5g. Density = mass/volume; volume = mass/density = volume of 1 mole of copper. You can find the volume of 4 atoms which are in a cube of known side length. Divide the total volume by volume of a cube to find how many 4 atom cubes fit in 1 mole - make sure units are consistent though.