how do you calculate the mass in grams for each of the following?

Question

a) 3.01 x 10^23 atoms of S (sulfur)

b) 2.41 x 10^24 molecules of H2O (water)

please include step by step instructions....

Answer 1

In both cases, divide by avogadro's number to convert atomr or molecules into moles, and then use the atomic weight or molar mass to convert moles into grams.

Answer 2

First of all, determine the atomic weight of your substance. Sulfer, for example, has an atomic weight of 32.065 amu. This means that a mole of sulfer will have a mass of 32.065 g.

A mole is 6.02 * 10^23 atoms or molecules.

So you take (3.01 * 10^23 / 6.02 * 10^23) * 32.065g = 16.032g.

For the H20, add the atomic mass of two hydrogens and one oxygen.