8.43g of CaCl2·2H2O is dissolved in 40.0g of H2O. What is the molality of the solution? (Note that the H2O in the CaCl2·2H2O must be included in the molar mass of the compound in order to calculate the moles of solute. Also note that the H2O contributed by this solute must be included in the total amount of solvent present in the solution in calculation of molality.

To calculate the molality of the solution, we need to first determine the number of moles of CaCl2·2H2O using its molar mass and then use the total mass of the solvent (water) to find molality.

Step 1: Calculate the molar mass of CaCl2·2H2O The molar mass of CaCl2·2H2O is the sum of the molar masses of each constituent atom multiplied by the number of each atom in the formula: Calcium (Ca): 40.08 g/mol Chlorine (Cl): 35.45 g/mol x 2 = 70.90 g/mol Water (H2O): 18.015 g/mol x 2 = 36.03 g/mol

Total molar mass of CaCl2·2H2O = 40.08 + 70.90 + 36.03 = 147.01 g/mol

Step 2: Calculate the moles of CaCl2·2H2O Number of moles = mass of solute (g) / molar mass of solute (g/mol) = 8.43 g / 147.01 g/mol ≈ 0.05735 moles

Step 3: Calculate the total mass of the water solvent The mass of water given is 40.0 g plus the mass of water from CaCl2·2H2O. Since there are 2 moles of H2O for each mole of CaCl2·2H2O, and each mole of H2O is 18.015 g, we have: Mass of water from CaCl2·2H2O = 0.05735 moles x 2 x 18.015 g/mol ≈ 2.067 g

Total mass of water solvent = 40.0 g + 2.067 g ≈ 42.067 g Convert to kilograms: 42.067 g / 1000 = 0.042067 kg

Step 4: Calculate the molality Molality (m) = moles of solute / kilograms of solvent = 0.05735 moles / 0.042067 kg ≈ 1.363 m

So, the molality of the solution is approximately 1.363 mol/kg.