posted by george .
Arginine vasopressin is a pituitary hormone. It helps regulate the amount of water in the blood by reducing the flow of urine from the kidneys. An aqueous solution containing 21.6 mg of vasopressinin 100.0 mL of solution has an osmotic pressure at 25 ¢ªC of 3.70 mmHg. What is the molecular mass of the hormone?
pi = osmotic pressure in atm.
pi = MRT
Substitute and solve for M = molarity.
M = mols/L. You have M and L, solve for mols.
Then mols = grams/molar mass. You have grams and mols, solve for molar mass.