he atomic radius of metal X is 1.20 × 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)

Question

aaronq · Answer

start with the density formula: $\rho=\dfrac{m}{V}$

in FCC there are 4 atoms per unit cell: $\rho=\dfrac{4*m_{atom}}{V}$

for FCC the edge of the unit cell is $a=r\sqrt{8}$, so:  $\rho=\dfrac{4*m_{atom}}{(r\sqrt{8})^3}$

last the mass of 1 atom is found by dividing the molar mass by $N_A$ (avogadros number)

$\rho=\dfrac{4*\dfrac{2.3\;g/mol}{N_A}}{(r\sqrt{8})^3}$

now you just need to convert the radius to units you want before plugging it in

anonymous · Answer

@Luigi0210  could you help me out here?

deadpoolroxz · Answer

https://answers.yahoo.com/question/index?qid=20150205233348AA1Mwi4

deadpoolroxz · Answer

that haz the answer

anonymous · Answer

my question has one of the numbers different, the radius is 125pm

hwyl · Answer

stop cheating  @deadpoolroxz

anonymous · Answer

i get how to do it and i've done the math 4 times now, i cant tell what i'm doing wrong

anonymous · Answer

http://openstudy.com/study#/updates/5406183de4b0f2ed1e152795