<p>I can't answer your first question because I cannot, for the life of me, remember chemical thermodynamics very well.</p>
<p>The second one though I can help with.
Osmotic pressure=iMRT. Since the protein is a non-electrolyte and doesn't dissociate, i=1. So we have 9.8mmHg=(1)M(0.0821 L<em>atm/mol</em>K)(298K).</p>
<p>You need to convert the osmotic pressure to atm. 1 atm=760 mmHg... you can do the conversion. So after converting to atm, we have 0.0129 atm=M(0.0821)(298).</p>
<p>Solving for M (the molarity), we get M=5.273<em>10^-4. Remembering that molarity is mols of solute/liters of solution, we can write 5.273</em>10^-4=x/0.100L, where "x" is the number of mols.</p>
<p>Solving for "x", we get 5.273<em>10^-5 mols. We are also given the mass, so we can write this as 5.273</em>10^-5 mols=0.200g. Divide to get the molecular weight in grams/mole: 3792.9 g/mol.</p>