- #106

Mr Real

- 122

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Yeah, I can see thatBorek said:First, the difference (understood as V_{vap}-V_{sub}) is getting lower and lower when we move to higher temperatures, see the first plot.

*but*I was talking about the absolute value of the difference in vapor pressures.

Okay, I didn't notice that, I thought the minimum was at 273 K in the plot.Borek said:Absolute value for the 1 molal solution for which the calculations were done has minimum at around 271.3 K (normal melting point minus cryoscopic constant). (Minimum value should lie on zero, just the plot is inaccurate).

Yes, I agree it doesn't grow initially.Borek said:So, if we move from 273 down, the difference gets lower till it hits zero, it doesn't grow, at least initially.

Well, I've been talking about the absolute value for all this time. The absolute value of the difference in vapor pressures is increasing whether we go to lower/higher temperatures (except when it decreases initially when we reduce temperature from 273 K to 271.3 K, as you said).Borek said:what really matters for us here, is the absolute value of the difference (second plot), as as long as the pressures are not equal system is not at the equilibrium, and it is the equilibrium that we are interested in (as this is where the new melting point is)

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