A complex is prepared by mixing cocl3 and nh3 in the molar ratio 1:4. 0.1 M of this complex was found to freeze -0.372 degree Celsius . what is the formula of complex.? kf water =1.86 C/ m?

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Explanation:

When cocl3 and nh3 are mixed in the molar ratio of 1:4, a complex of the form CoCl3.4NH3 is formed.

The freezing point depression, ΔTf, is given by the formula ΔTf = Kf x m x i, where Kf is the freezing point depression constant of water, m is the molality of the solution, and i is the van't Hoff factor.

In this case, the molality, m, can be calculated as follows:
- 1 mole of CoCl3.4NH3 contains 4 moles of NH3.
- Therefore, the total number of moles of solute = 1 + 4 = 5.
- The mass of 5 moles of solute can be calculated as follows:
  - 1 mole of CoCl3 weighs 165.3 g/mol
  - 4 moles of NH3 weigh 68 g/mol x 4 = 272 g/mol
  - Therefore, the mass of 5 moles of solute = 165.3 g/mol + 272 g/mol = 437.3 g/mol
- The molality, m, is given by m = moles of solute / mass of solvent (in kg).
- Assuming that 0.1 L of solution is used, the mass of water = 100 g.
- Therefore, the molality, m, can be calculated as follows:
The van't Hoff factor, i, is equal to the number of particles into which the solute dissociates in solution. In this case, the complex does not dissociate in solution, so i = 1.

Substituting the values of Kf, m, and i into the formula for ΔTf, we get:

ΔTf = 1.86 x 50 x 1 = 93.0 C

However, the question asks for the freezing point depression, which is -0.372 C. This is because the freezing point depression is negative, as the freezing point of the solution is lower than that of pure water.

The actual value of ΔTf is therefore -0.372 C.

Finally, we can use the formula ΔTf = Kf x m x i to calculate the molality, m, of the solution.

m = ΔTf / (Kf x i) = -0.372 / (1.86 x 1) = -0.2 mol/kg

The negative sign indicates that the solution is supercooled, i.e. it is still in the liquid state at a temperature below its freezing point.

Since the molality of the solution

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