How many grams of Co are there in a sample of Co that contains the same number of moles as a 45.6 gram sample of Cr?

The atomic weight of Cr is 52.0 g/mol

1. Convert grams of Cr to moles of Cr:

moles Cr = 45.6 g Cr1 mol = 0.877 mol Cr52.0 g

Multiply by moles per gram. Grams cancel out.

The atomic weight of Co is 58.9 g/mol

2. To convert 0.877 moles of Co to grams of Co:

grams Co = 0.877 mol Co58.9 g = 51.7 g Co

1 mol

Multiply by grams per mole. Moles cancel out.

Note that since the atomic weight of Co is larger than the atomic weight of Cr, the mass of the same number of moles is also larger.