Question

Calculate the number of atoms in a 3 inch diameter sphere of iridium.

Answer 1

volume of sphere (V) = (4/3)*pi*r^3

diameter = 2r = 3 inch

r =radius = 3/2= 1.5 inch = 3.81 cm

volume = (4/3)*3.14*(3.81)^3 =231.55 cm^3

mass of iridium(Ir) = d*v

         d = density of Ir = 22.56 g/cc

    m = 22.56*231.55 = 5223.8 g

no of mol of Ir = 5223.8/192 =27.21 mol

no of atoms of Ir = 27.21*6.023*10^23

                  = 1.64*10^25 ATOMS