Considering the Avogadro number, we know that there is 6,022 x 10^23 molecules of NaOH in 1 mol of NaOH, and we need to calculate how much in mols we would have for 2.90 ×10^22 molecules:
6,022 x 10^23 molecules ------- 1 mol
2.90 ×10^22 molecules ---------- x
[tex]x\text{ = }\frac{\text{1 mol of NaOH}\times(2.90\times10^{22}\text{molecules of NaOH)}}{(6.022\times10^{23}\text{ molecules of NaOH)}}[/tex]Solving for x, we have 0.048 mol of NaOH.
Now we calculate how much, in mass, 0.048 mol of NaOH is:
1 mol ---------- 40.0 g
0.048 mol ---------- y
Solving for y, we have 1.92 g of NaOH
