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A solution is prepared by dissolving 1.08 g of human serum albumin in 50.0 mL of water. The solution has an osmotic pressure of 5.85 mmHg at 298 K. What is the molar mass of human serum albumin?
Answer:
We need to use the relationship between osmotic pressure and solution concentration:
p = nRT / V
For our problem:
p = osmotic pressure
n = moles of substance = m / MW = mass / molecular weight
R = 0.08206 L atm mol-1 K-1 = ideal gas constant
T = temperature (in Kelvin)
V = volume (in atmospheres)
Rearrange the equation to solve for MW:
MW = mRT / pV
MW = (1.08 g * 0.08206 L atm mol-1 K-1 * 298 K) / (7.70 x 10-3 atm * 0.0500 L)
MW = 6.86 x 104 g/mol
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