Calculate the molecular weight of a small protein if a 0.25-g sample dissolved in 180 mL of water has an osmotic pressure of 9.2 mmHg at 25°C.(R = 0.0821 L · atm/(K · mol)) A)2.4 × 10² g/mol B)2.8 × 10³ g/mol C)3.6 g/mol D)2.7 × 10² g/mol E)3.7 × 10^-3 g/mol

Question

Quizplus · Accepted Answer

To find the molecular weight, use the formula for osmotic pressure: π = (n/V)RT. Convert 9.2 mmHg to atm (9.2/760), and 180 mL to L (0.180 L). Solve for n (moles), then use the mass (0.25 g) to find the molecular weight: MW = mass/n. The calculation gives approximately 2800 g/mol.

Calculate the Molecular Weight of a Small Protein If a 0.25-G