A nanotechnology equipment requires 7.40 x 10^18 atoms of potassium. What is the mass of this sample?

4.81*10⁻⁴ g K

Explanation:

Convert atoms to moles:

7.40*10¹⁸ atoms K * (1 mol K / 6.02*10²³ atoms) = 1.23*10⁻⁵ mol K

Convert moles to mass:

1.23*10⁻⁵ mol K * (39.1 g K / mol K) = 4.81*10⁻⁴ g K