When 18 g of ethylene glycol C2H6O2 is dissolved in 150 g of pure water, the freezing point of the solution is

_____ C. (The freezing point depression constant for water is 186C kgmol.

moles ethylene glycol = grams/molar mass

solve for moles ethylene glycol.

molality = mols/kg solvent
solve for molality

delta T = Kf*m
solve for delta T

Subtract delta T from zero C to obtain the freezing point.

b. What is the freezing point depression when 153 g of bromine is added to 100 g of benzene?

To find the freezing point of the solution, we need to calculate the freezing point depression caused by the dissolved ethylene glycol.

Freezing point depression is given by the equation:

∆Tf = Kf × m

where:
∆Tf is the freezing point depression
Kf is the freezing point depression constant for the solvent (in this case, water)
m is the molality of the solute (ethylene glycol)

First, let's calculate the molality (m) of the solution:

Molality (m) = moles of solute / mass of solvent (in kg)

To find the moles of ethylene glycol, we'll use its molar mass:

Molar mass of C2H6O2 = (2 × 12.01 g/mol) + (6 × 1.01 g/mol) + (2 × 16.00 g/mol)
= 62.07 g/mol

moles of ethylene glycol = mass of ethylene glycol / molar mass of ethylene glycol
= 18 g / 62.07 g/mol

Now, let's convert the mass of water to kilograms:

mass of water = 150 g = 150 g / 1000 g/kg = 0.150 kg

Now we can calculate the molality (m):

m = moles of solute / mass of solvent (in kg)
= (18 g / 62.07 g/mol) / 0.150 kg

Next, we need to calculate the freezing point depression (∆Tf) using the freezing point depression constant for water (Kf):

∆Tf = Kf × m
= 1.86 °C kg/mol × (moles of solute / mass of solvent in kg)

Finally, we can calculate the freezing point of the solution:

freezing point of solution = freezing point of pure solvent - ∆Tf

Since the freezing point depression (∆Tf) is subtracted from the freezing point of the pure solvent, the equation becomes:

freezing point of solution = 0 °C - ∆Tf

Substituting the calculated ∆Tf value that we obtained earlier into this equation will give us the final freezing point of the solution.