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(a) Sodium metal crystallizes in bcc structure. Its unit cell edge length is 420 pm. Calculate its density. (Atomic mass of sodium = 23 u, N_(A) = 6.022 xx 10^(23) mol^(-)). (b) What is Frenkel defect ? How does it affect the density of a crystal ? |
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Answer» Solution :(a) Density `= (Z.M)/(a^(2) N_(A))` `= (2 XX 23 xx 10^(-3))/(420 xx 10^(-12) xx 6.022 xx 10^(23))` `= 1.031 xx 10^(3) kg//m^(3)` (b) This is a defect caused by the DISLOCATION of a smaller ION from its normal site to an intersitial site. Density does not change. |
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