How many unit cells can be made out of an 18 carat pure 197 g sample of gold ?( FCC structure A = 197 u)?

Answer 1

First find out normal unit cell that is by formula!... n×NA/Z..this will be the no of unit cells in 24 carat so.. Using unitary method find no of unit cell in 18 carat gold

Answer 2

First ball find out how many moles are given so we know that 197 grams of 18 carat gold is given hence one mole of 18 carat gold is present.. one fcc unit cell give the question has four particles..( 8 at the corners and 12 at face centre) previously we found that we have one mole of substance one mole of substance has NA amount of particles hence unitary method NA particles will have NA by 4 unit cell.... If it was 24 carat gold any by 4 unit cell was the answer but there is 18 carat gold given so show by unitary method we can solve or we could say that 24 carat gold is 100% pure but 18 karat gold is 75% pure so (NA by 4 ) X 75/100 = (3/16)NA this is ans