Question

How many grams of bariium hydroxide required to dissolve in 156 g of water to make .247 m solution?

Answer 1

6.60g of Ba(OH)2 is required.

Explanation:

To answer this question, we need two things:

The molar mass of barium hydroxide, 171.34 g/mol

We are given the molality and mass of solvent. The mass of solvent is expressed in terms of grams and we need kilograms so the following relationship must be used:

1000g = 1kg

Divide 156g by 1000 to obtain 0.156 kg of solvent.

Next, we determine the number of moles of solute (barium hydroxide), by rearranging the equation:

Moles of solute = Molality x Mass of solvent

Therefore, 0.247m×0.156kg = 0.0385molBa(OH)2

Since we want the mass of Ba(OH)2, the number of moles of solute must be multiplied by the molar mass of the solute:

0.0385mol×171.34g1mol

g Ba(OH)2 = 6.60g