Chemistry Help Forum Face centered cubic question
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 Dec 7th 2016, 09:04 PM #1 starrysky Junior Member   Join Date: Oct 2016 Posts: 10 Face centered cubic question The atomic radius of metal X is 1.50 × 102 picometers (pm) and a crystal of metal X has a unit cell that is face-centered cubic. Calculate the density of metal X (atomic weight = 42.3 g/mol).
Dec 8th 2016, 01:26 PM   #2
topsquark
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 Originally Posted by starrysky The atomic radius of metal X is 1.50 × 102 picometers (pm) and a crystal of metal X has a unit cell that is face-centered cubic. Calculate the density of metal X (atomic weight = 42.3 g/mol).
The main concept here is to find the density of the material...ie. from a single unit cell. So for an FCC crystal how many atoms of X are in the unit cell? What are the dimensions of the unit cell? So now you know the density in terms of # of atoms/volume in a unit cell. The rest is unit conversions.

Does this help or do you need more?

-Dan
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 Apr 16th 2019, 11:15 PM #3 chemistrystudy Junior Member   Join Date: Jan 2019 Location: India Posts: 8 We know that σ = (Z × M)/(N × a³) Here, Z = 4 for fcc cubic Crystal, M = 42.3 gm/mol and N = 6.023 × 10²³ and a = 1.50 × 10² pm = 1.50 × 10⁻⁸ cm Putting the value on the above equation to calculate the density of the crystal X.

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