Question

What is the molality of a solution that contains 31.0 g HCI in 5.00 kg water?

Answer 1

The molar mass of HCl is:
Molar mass (H) + Molar mass (Cl) = 1.007 g/mol + 35.453 g/mol = 36.460 g/mol

Now, calculate the number of moles of HCl:
moles = mass / molar mass
moles = 31.0 g / 36.460 g/mol ≈ 0.850 mol

Next, calculate the mass of water (solvent) in kilograms:
mass of water = 5.00 kg

molality = moles of solute / mass of solvent (in kg)
molality = 0.850 mol / 5.00 kg ≈ 0.170 m