Question

If the molar mass of the substance is 20.0 g/mol, what is the mass of 3.01 x 10²⁵ molecules of the substance?

Answer 1

Find the number of moles in 3.01 x 10²⁵ molecules of the substance:

$$n=N/N_a=50\text{ mol}.$$

The mass:

$$m=n\Mu=50·20=1000\text{ g}.$$