Question

If the aluminum unit cell exhibits face-centered behavior then how many unit cells are present in 54g of aluminum?

(a) 1.2042 x 10^24

(b) 5.575 x 10^21

(c) 3.011 x 10^23

(d) 2.4088 x 10^24

This question was addressed to me in my homework.

I want to ask this question from Solid State in chapter Solid State of Chemistry – Class 12

Answer 1

Right answer is (c) 3.011 x 10^23

For explanation: Atomic mass of Al = 27g/mole (contains 6.022 x 10^23 Al atoms)

Since it exhibits FCC, there are 4 Al atoms/unit cell.

If 27g Al contains 6.022 x 10^23 Al atoms then 54g Al contains 1.2044 x 10^24atoms.

Thus, if 1 unit cell contains 4 Al atoms then number of unit cells containing 1.2044 x 10^24 atoms=(1.2044 x 10^24 x 1)/4 = 3.011× 10^23 unit cells.