Question

What is the molecular mass of a substance X if 1.00 L of a solution containing 4, 5 g of X has an osmolality of 0.337 mmHg the 30° C?

Answer 1

∏ = MRT = [moles/Vol(Liters)]RT => moles = (∏·Vol(Liters)/RT) = mass(gms)/Mol Wt

Solve for Mol Wt = [mass(gms)·R·T/∏·Vol(Liters)]

Mass = 4.5-gms
R = (0.08206 L-Atm/mole-K)
T = (30 + 273)K = 303K
∏ = (0.337/760)Atm = 4.4 x 10^-4 Atm
Vol(Liters) = 1.00 Liters

Substitute into Mol Wt Equation above => 252,000 g/mol

Answer 2

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