Answer to Question #90200 in Physical Chemistry for Anant sahu

Question

If carbon-carbon Bond length in diamond is 1.5 angstorm then what will be the edge length of the cubic closed packed unit cell of diamond having alternate tetrahedral voids occupied?

Answer 1

Given:

$$r_{c-c} = 1.5 { \ \ Angstrom }$$

Solution:

CCP cell:

From triangle ABC:

$$AB= r_{c-c}$$ $$AC= \sqrt{\frac{(AB)^2}{2} }$$

Edge length is:

$$L = 2 * AC = 2 * \sqrt{\frac{(AC)^2}{2}} = \sqrt{2(AC)^2} = \sqrt{2r_{c-c}^2}$$

Calculating:

$$L =\sqrt{2r_{c-c}^2} = \sqrt{2*1.5^2}\approx 2.12 \ Angstrom$$

Answer: 2.12 Angstrom

References:

• https://hemantmore.org/chemistry-1/c11201018/1899/