An alloy of iron (53.6 %), nickel (45.8 %) and maganese (0.6 %) has a density of `8.17 "g cm"^(-3)`. Calculate the number of Ni atoms present in the alloy of dimensions `10.0 cm xx 20.0 cm xx 15.0 cm`.

Explanation

Step I. Calculation of mass of nickel (Ni) in the alloy
Volume of the alloy `= (10.0 cm)xx(20.0 cm)xx(15.0 cm)= 3000 cm^(3)`
Mass of the alloy = Density `xx` Volume `= (8.17 "g cm"^(-3))xx(3000 "cm"^(3))=24510 g`
Mass of Ni in the alloy `= (24510 g)xx(45.8)/(100) = 11225.6 g`
Step II. Calculation of number of nuckel (Ni) atoms in the alloy
Gram atomic mass of Ni = 59 g
59 g of Ni have atoms `= 6.022 xx 10^(23)`
`11225.6 g` of Ni have atoms `= 6.022 xx 10^(23) xx ((11225.6g))/((59.0g))=1.15xx10^(26)` atoms .