Question

A solution of barium hydroxide, `Ba(OH)_2` contains 4.285 grams of barium hydroxide in 100 mL of solution. What is the molarity of the solution?

Answer 1

2.5 M

Explanation:

We know the molar mass of barium hydroxide is 171.34 (you can google this or just add the mass of each atom in the molecule). Knowing that `molarity = (mols) / (liters)` we need to turn that 4.285 g Ba(OH)2 into mols.

This is done by dividing 4.285 g by the 171.34 g molar mass giving us 0.2500 mol of Ba(OH)2.

Plugging this all back into the equation for molarity we get `molarity = (0.2500 mol)/(0.100 L)` giving us a molarity of 2.5 M