Atomic mass Co = 58.93
Atomic mass 3 Br = 3 x 79.90 = 239.7
Total = 298.6
0.0404% by weight means, 0.0404 g of CoBr3 in 100g of
solution
Hence, from the molecular formula and molar
mass,
        298.6 g
of CoBr3 --- 239.7 g of Br is present
So,   0.0404 g of CoBr3 ---- >
(0.0404 * 239.7) / 298.6 = 0.0324 g of Br
Therefore, 100g of solution contains 0.0324g of
Br
                           Â
= 0.0324 g / 100 g of solution
                           Â
= 0.000324 g/ g of solution
Hence in ppm it must be,
                           Â
= 0.000324 * 10^6 ug /g
                            Â
= 324 ppm
