What would the boiling point be of 300 ml with 40 g CuCl2 dissolved in it?
To determine the boiling point of a solution, you need to consider the colligative properties of the solute (CuCl2) dissolved in the solvent (water). One such property is called boiling point elevation.
The boiling point elevation is defined as the difference between the boiling point of the pure solvent and the boiling point of the solution. It depends on the concentration of the solute in the solution. In this case, we have 40 g of CuCl2 dissolved in 300 ml of solvent (water).
To calculate the boiling point elevation, you need to know the molality of the solution. Molality (m) is defined as the number of moles of solute per kilogram of solvent.
First, let's calculate the number of moles of CuCl2:
Number of moles = mass of solute / molar mass of solute
The molar mass of CuCl2 is 63.546 g/mol (copper: 63.546 g/mol + chlorine: 35.453 g/mol x 2 = 70.906 g/mol).
Number of moles = 40 g / 70.906 g/mol ≈ 0.563 mol
Next, we determine the mass of the solvent (water) in kilograms:
Mass of solvent = volume of solvent x density of solvent
Given that the volume of water is 300 ml and the density of water is approximately 1 g/ml:
Mass of solvent = 300 ml x 1 g/ml = 300 g = 0.3 kg
Now we can calculate the molality of the solution:
Molality (m) = number of moles of solute / mass of solvent (in kg)
Molality (m) = 0.563 mol / 0.3 kg ≈ 1.877 mol/kg
Finally, we use a proportionality constant called the boiling point elevation constant (Kb) specific to water, which is approximately 0.512 °C/m.
The boiling point elevation (ΔTb) is calculated as:
ΔTb = Kb * m
ΔTb = 0.512 °C/m * 1.877 mol/kg
ΔTb ≈ 0.963 °C
Therefore, the boiling point elevation caused by dissolving 40 g of CuCl2 in 300 ml of water is approximately 0.963 °C.
To find the boiling point of the solution, you will need to add the boiling point elevation to the boiling point of the pure solvent (water). The boiling point of pure water is 100 °C (at sea level), so the boiling point of the solution will be:
Boiling point of solution = boiling point of solvent + boiling point elevation
Boiling point of solution = 100 °C + 0.963 °C
Boiling point of solution ≈ 100.963 °C
Hence, the boiling point of the solution containing 300 ml of water with 40 g of CuCl2 dissolved in it would be approximately 100.963 °C.