The normal freezing point of a certain liquidxis0.4°c, but when5.90gof ureanh22coare dissolved in450.gofx, it is found that the solution freezes at−0.5°cinstead. use this information to calculate the molal freezing point depression constantkfofx.

The molal freezing point depression constant for X is 4.12 °C/m

Explanation:

Apply the colligative property of freezing point depression:

ΔT = Kf . m . i

We assume the X lquid is non electrolytic, so i = 1

ΔT = T° freezing point of solvent pure - T° freezing point of solution

m = molality (moles of solute in 1kg of solvent)

Kf = Cryoscopic constant (the data we were asked for)

ΔT = 0.4° - (- 0.5°) = 0.9°

Let's calculate molality

Molar mass of urea = 60.06 g/m

Moles of urea = mass of urea / molar mass

5.90 g / 60.06 g/m = 0.098 moles

This moles are in 450 g of solvent, prepare a rule of three to find out the moles in 1000 g

450 g 0.098 m

1000 g ( 1000.  0.098)/450 = 0.218 m

0.9° = Kf . 0.218 m . 1

0.9° / 0.218 m = Kf → 4.12 °C/m

they it depends on if one believes about radioactivity, they make a geiger counter beep but maybe it was going to beep anyway electronics do wierd things all the time or it was programmed to beep near certain metals.

it is the most commonly accepted one