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Let's say that I have a solution of some substance in some solvent. The density of the solute is $\rho_\text{solute}$ and the density of the solvent is $\rho_\text{solvent}$. Suppose that the osmotic pressure of this solution is $$\Pi(\gamma) = k\gamma$$ where $k$ is some constant. We know that osmotic pressure is generally given by $$\Pi = icRT.$$ If we express the molar concentration as $c = \gamma / M$ and rearrange the equation, we get $$\Pi(\gamma) = \frac{iRT}{M}\gamma.$$ That means that $$k = \frac{iRT}{M}.$$ Now, if I know the constant $k$, but not the temperature $T$, that means that I can't calculate the molar mass $M$? Is there maybe another way to calculate it? Perhaps using the given densities? Thank you in advance.

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    $\begingroup$ Well, the temperature can be determined from the density of the solvent. Or estimated. $\endgroup$
    – Poutnik
    Sep 7, 2023 at 14:02
  • $\begingroup$ By that, do you mean looking at charts or something else? @Poutnik $\endgroup$ Sep 7, 2023 at 14:53
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    $\begingroup$ Charts or using empirical formulas. But estimation of T could be good enough. $\endgroup$
    – Poutnik
    Sep 7, 2023 at 14:55
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    $\begingroup$ If you have been able to calculate the constant $k$ in an osmosis experiment, it means that you know the formula and the molar mass of the solute (and the temperature). $\endgroup$
    – Maurice
    Sep 7, 2023 at 16:33
  • $\begingroup$ I was given the value of $k$ and need to find out the molar mass. $\endgroup$ Sep 7, 2023 at 19:22

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