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?

1 Answer
May 9, 2018

2.5 M


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