Question

A solution is made by dissolving 100. g of cobalt(III)chloride in 250. g of water. to make a solution that has a density of 1.25 g/mL. Calculate (I) the molality and (II) the molarity of the solution.A)(I) 2.42 m(II) 2.16 MB)(I) 2.16 m(II) 2.42 MC)(I) 0.400 m(II) 0.500 MD) (I) 0.0417 m(II) 0.0522 ME)(I) 0.0522 m(II) 0.0417 M

Answer 1

Answer:

Option A) (I) 2.42 m (II) 2.16 M

Explanation:

Let's determine some information.

Solute = CoCl₃ (molar mass = 165.29 g/m); mass of 100 g

Solvent = Water, mass of 250 g

Solution mass = mass of CoCl₃ + mass of water

250 g + 100 g = 350 g of solution

If we want to reach molarity (mol/L), let's determine solution volume with density:

Solution density = solution mass / solution volume

1.25 g/mL = 350 g / solution volume

Solution volume = 350 g / 1.25 g/mL = 280 mL

Let's convert the volume to L → 280 mL = 0.280L

Let's convert the mass of solute to moles = 100 g / 165.29 g/m →0.605 mol

Mol/L = 0.605 moles / 0.280 L = 2.16 M

Now let's calculate molalilty (mol/kg of solvet)

We must convert solvent mass to kg → 250g = 0.250 kg

Then, 0.605 moles / 0.250 kg =2.42 m