2
$\begingroup$

Have a dissolution with $12$g of an unknown polymer for each liter of solution at $25^\text{o}$C has an osmotic pressure of $12.1$ torr. What is the molar mass of the polymer?

Apparently the formula for osmotic pressure is

$$M\cdot R\cdot T$$

That's

$$0.0159 = M\cdot 0.0821\cdot 298$$

Therefore the molarity is

$$M = \frac{0.0159}{0.0821\cdot 298} = 0.000649$$

The formula for Molarity is

$$\frac{\text{moles of this polymer}}{\text{liters of dissolution}} = 0.000649$$

They ask me for the molar mass of the polymer, but how do I find it?

$\endgroup$
2
$\begingroup$

You have 0.000649 moles of something that weighs (has a mass of) 12 g. Thus, molar mass is: $${12\;{\rm g}\over 0.000649\;{\rm mol}} = 18490\;{\rm g\over mol}$$

$\endgroup$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.