A 21 mL HCl solution is titrated with 11.6 mL of a 0.55 M KOH solution. What is the concentration of the HCl solution?

0.058 g of Al₂O₃

Explanation:

Al₂O₃ → Aluminum oxide

The molar mass is 101.96 g/mol. Therefore 1 mol (NA molecules) are contained in 101.96 grams

NA = Avogadro's number → 6.02×10²³

We make a rule of three to determine the grams we were asked for.

6.02×10²³ molecules are contained in 101.96 g

3.45×10²⁰ molecules will be contained in (3.45×10²⁰ . 101.96 g ) / NA = 0.058 g