Calculate the mole fraction of Ba Cl 2 in an aqueous solution prepared by dissolving 0.400 moles of Ba Cl 2 in 850.0 g of water.

0.0084

Explanation:

The mole fraction of BaCl₂ (X) is calculated as follows:

X = moles BaCl₂/total moles of solution

Given:

moles of BaCl₂ = 0.400 moles

mass of water = 850.0 g

We have to convert the mass of water to moles, by using the molecular weight of water (Mw):

Mw of water (H₂O) = (2 x 1 g/mol)+ 16 g/mol = 18 g/mol

moles of water = mass of water/Mw of water = 850.0 g/(18 g/mol) = 47.2 mol

The total moles of the solution is given by the addition of the moles of solute (BaCl₂) and the moles of solvent (water):

total moles of solution = moles of BaCl₂ + moles of water = 0.400 + 47.2 mol = 47.6 mol

Finally, we calculate the mole fraction:

X = 0.400 mol/47.6 mol = 0.0084