[FeLiXe]

Hello could someone help me with this:

I would like to adjust data from cryoscopy by the Debye-Hückel law. Does someone know how that works? My problem is that my solution does not behave ideally anymore and I would like to know what to do.

How do I get the activity coefficient of water when I have the activity coefficient of the salt?

thanks

[Borek]

How do I get the activity coefficient of water when I have the activity coefficient of the salt?

Water molecules are not charged, so its activity coefficient is 1. At least in the range where D-H law can be used.

[FeLiXe]

thanks for the quick answer

I am sorry, I have just noticed that I can't use the D-H law because I have between .3 and 1 mol / kg

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actually I also have some other data to use but it seems even more difficult to apply (we don't have to do that but it be cool if I could find something)

we measured the mixing enthalpy of adding 25mL water to 25mL solution

it was 98J (.1 J/mol water) for 1 mol/kg solution and
35 J (.04 J/mol water) for .5 mol/kg solution

I am wondering how those non-ideality effects change the melting point. the melting point we measured for the more concentrated solutions was to high. but I don't know how to put it into formulas

[FeLiXe]

I found something to do: comparing the measured mixing enthalpy with the ideal mixing Gibbs energy