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molar mass= grams /moles , so we need to find the grams and divide that # by the number of moles 1. Set up this equation and place the grams on top. Now you need to find the moles to complete the problem.
2. Find the Molarity using osmotic pressure and temperature p=MRT so
3. Find the moles of solute from molarity by multiplying by the liters of solution.
so 4. Now that you have the moles, plug it back into the equation from step 1 and solve for molar mass.
Example-Molar Mass from Osmotic Pressure An aqueous solution contains 0.97g/L of an organic compound. The osmotic pressure of this solution is 62.9 torr, at 25°C. What is the molar mass of this compound?
1. Set up this equation and place the grams on top. Now you need to find the moles to complete the problem.
2. Find the Molarity using osmotic pressure and temperature p=MRT
3. Find the moles of solute from molarity by multiplying by the liters of solution. 0.0338M=0.0338mol/L since assumed 1 L 0.0338mol 4. Now that you have the moles, plug it back into the equation from step 1 and solve for molar mass.
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