A solution is prepared by placing 72.8 g of magnesium chloride in 120 g of water at 22oC.

a)What is the boiling point of the solution?

b)What is the freezing point of the solution?

For a.

delta T = i*Kb*molality

For b.
delta T = i*Kf*molality
Post your work if you get stuck.
molality = grams/kg solvent

109.4

To determine the boiling point and freezing point of the solution, you will need to use the concept of colligative properties. These properties depend on the number of particles in a solution, rather than the nature of the particles themselves.

a) To find the boiling point of the solution, you need to calculate the change in boiling point caused by the presence of the solute (magnesium chloride).

The boiling point elevation (ΔTb) is given by the equation:

ΔTb = Kb * m

where Kb is the molal boiling point elevation constant and m is the molality of the solution.

1. Firstly, calculate the molality of the solution.
Molality (m) = moles of solute / mass of solvent (in kg)

Given:
Mass of magnesium chloride (solute) = 72.8 g
Mass of water (solvent) = 120 g = 0.120 kg

To calculate moles of solute, you need to know the molar mass of magnesium chloride (MgCl2), which is approximately 95.211 g/mol.

Moles of solute = mass of solute / molar mass of solute
= 72.8 g / 95.211 g/mol

2. Calculate molality (m).
Molality (m) = moles of solute / mass of solvent (in kg)
= ( moles of solute ) / ( mass of water in kg )
= (72.8 g / 95.211 g/mol) / 0.120 kg

b) To find the freezing point of the solution, you need to calculate the depression in freezing point caused by the presence of the solute (magnesium chloride).

The freezing point depression (ΔTf) is given by the equation:

ΔTf = Kf * m

where Kf is the molal freezing point depression constant.

Follow steps 1 and 2 to calculate the molality (m) of the solution.

Once you have calculated the molality (m) for both parts a) and b), you can substitute the calculated molality values into the equations for boiling point elevation (ΔTb) and freezing point depression (ΔTf), respectively.

Finally, to find the boiling point and freezing point of the solution, use the equations:

Boiling point = boiling point of the solvent + ΔTb
Freezing point = freezing point of the solvent - ΔTf

The boiling point and freezing point of the solvent (water) can be found in reference tables or online resources.