[Vaubon]

Hi to all,

I am struggling with my big school project in chemistry.
My experiment was to elevate the freezing point of 1-Dodecanol (solvent) by adding ethanol (solute) in order to determine ethanol's molar Mass. I know the formula is t=Kf x m . My first problem is that I don't know Kf for 1-Dodecanol. On the internet I found a value that was 2.9, however, when I calculated the molar mass with it I got 167 but it should be 46. My values from my experiment were :
t= 2.2 (freezing point of both mixed together subtracted by freezing point of dodecanol alone)
mass of dodecanol= 8.9g
mass of ethanol=1.1g
Can someone please help me to figure out what I did wrong?? My teacher is not allowed to give me any support or tips. I really have no idea what I should do and I've ran out of ways to find an answer.

Thanks so much for your helps !!

[Borek]

I am afraid your project is based on some faulty assumptions.

I know the formula is t=Kf x m

This formula works best for diluted, non volatile solutes. You solute is neither diluted (at 2.7 m it is quite concentrated) nor non volatile.

You can try to get better results not by using some random Kf found on Internet, but by measuring it first with some other solute of known molar mass. Still, what I wrote above makes the process unlikely to give reasonably correct results.

[Enthalpy]

[...] elevate the freezing point [...]

Doubt.

[Vaubon]

Hi there,

I have a major assignment in Chemistry and I need to calculate something. However, I need Kf -the freezing point depression constant- for 1-dodecanol.I already searched for it in books and on the internet in english, german and russian and I can't find it! I have tried, I really have but I really need a clue. Any thoughts about a reliable and reference-able source??

Thanks for your *delete me*!