what is the freezing point of 16.7g of LiCl in 136g of water, assuming complete dissociation for water kf= -1.86/mol

mols LiCl = grams/molar mass.

Solve for mols.

m = mols/kg solvent
Solve for m

delta T = i*Kf*m
Solve for delta T and subtract from norma freezing point. i for LiCl = 2.

To find the freezing point of a solution, we can use the formula:

ΔT = kf × molality

Where:
ΔT is the change in temperature,
kf is the freezing point depression constant (also known as the cryoscopic constant),
and molality is the molal concentration of the solution.

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

m = moles of solute / kilograms of solvent

Given that the mass of LiCl is 16.7g and the mass of water is 136g, we need to convert these masses to moles:

Molar mass of LiCl = atomic mass of Li + atomic mass of Cl = 6.94 g/mol + 35.45 g/mol = 42.39 g/mol

moles of LiCl = mass of LiCl / molar mass of LiCl = 16.7g / 42.39 g/mol

Similarly, for water, the molar mass is 18.015 g/mol:

moles of water = mass of water / molar mass of water = 136g / 18.015 g/mol

Now we have the moles of solute (LiCl) and the kg of the solvent (water). We can calculate the molality:

molality = moles of solute / kilograms of solvent

Finally, we'll use the formula mentioned earlier to find the change in temperature (ΔT) or the freezing point depression:

ΔT = kf × molality

Given that kf is -1.86 °C/m, substitute the values to find ΔT.