Question

Potassium crystallize in a bcc lattice with density 0.856g per cm3. Calculate the radius of k atom and the edge length of cell.

Answer 1

Answer:

Solution:

1) Convert pm to cm:

330.6 pm x 1 cm/1010 pm = 330.6 x 10¯10 cm = 3.306 x 10¯8 cm

2) Calculate the volume of the unit cell:

(3.306 x 10¯8 cm)3 = 3.6133 x 10¯23 cm3

3) Calculate mass of the 2 tantalum atoms in the body-centered cubic unit cell:

16.69 g/cm3 times 3.6133 x 10¯23 cm3 = 6.0307 x 10¯22 g

4) The mass of one atom of Ta:

6.0307 x 10¯22 g / 2 = 3.015 x 10¯22 g

5) The atomic weight of Ta in g/mol:

3.015 x 10¯22 g times 6.022 x 1023 mol¯1 = 181.6 g/mol