SOLUTION: trying to find the edge length of a unit cell. Potassium metal has a body-centered cubic structure with all atoms at the lattice points. The density of the metal is 0.856g/cm3. C

Question 211597This question is from textbook General Chemistry
: trying to find the edge length of a unit cell. Potassium metal has a body-centered cubic structure with all atoms at the lattice points. The density of the metal is 0.856g/cm3. Calculate the edge legth of a unit cell. I got m=M/Na=39.1g/mol/6.02x10x23atoms/mol= 6.49501661x10-23g/atom. write as 6049501661x10-23g/1atom x 2atoms/1unit cell= 1.29900332x10-22 g/unti cell then using density to find volume v=m/d 1.2990332x10-22g/0.856g/cm3=1.517527243x10-22cm3. then find edge legth v=l3 (volume =length cubed) so l=3 square root of volume = (1.517527243x10-22cm3) 1/3 = 5.333907732x10-8cm. this is my problem i dont know how to find the length = 3 square root on the calculator i have a ti-84 can you please show me how to do this final step on the calculator? thanks This question is from textbook General Chemistry

Answer by scott8148(6628) (Show Source): You can put this solution on YOUR website!
the symbol for potassium is K (Na is sodium)

the density is given to 3 significant figures
___ calculating with more SF than 3 is counterproductive

39.1g/mol / 6.02x10^23atoms/mol = 6.50x10^-23g/atom

1.30E-22 g per unit cell

1.30E-22g / .856g/cm^3 = 1.52E-22cm^3 = 152E-24cm^3

taking cube root ___ 5.34E-8cm

there should be a root key on your calculator for whole number roots

using laws of exponents ___ cube root (x) = x ^ (1/3)
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