Question

What is the mass in grams of 1.50 X 1023 molecules of NaOH?

Answer 1

Answer:

a. 10.0 g

Explanation:

The molar mass of NaOH is 39.997 grams which was calculated by adding the molar mass of Sodium, Oxygen, and Hydrogen $22.990 + 15.999 + 1.008 = 39.997$. But before we do anything with this number we must first convert $1.50 * 10^{23}$ molecules to moles. We can do this by dividing by Avogadro's number or $6.022*10^{23}$  ( $\frac{1.50*10^{23}}{6.022*10^{23}} = 0.24909$ moles). We then convert moles to grams by multiplying by the molar mass of NaOH, ($0.24909 * 39.997 = 9.96$ grams). This is almost exactly 10 and the margin of error is likely due to the original numbers not being precise enough.