Question

How many moles of Cr are there in 85 g of `Cr_(2) S_(3) ` ? (Cr = 52 , S = 32 )

Answer 1

Molecular mass of `Cr_(2)S_(3) = 2 xx 52 + 3 xx 32 = 104 + 96 = 200`
200 g of `Cr_(2)S_(3)` contains 104 g of Cr.
`therefore` 85 g of `Cr_(2)S_(3)` contains `(104 xx 85)/(200) "" g` of Cr = 44.2 g
Thus , number of moles of Cr = `(44.2)/(52) = 0.85` .