Calculate the osmotic pressure at 298 K of a solution made by dissolving 0.10 g of CaCl₂ in water and diluting to 100 mL.

Question

Quizplus · Accepted Answer

First, we need to calculate the molarity of the solution: moles of CaCl₂ = 0.10 g / 111 g/mol (molar mass of CaCl₂) moles of CaCl₂ = 0.0009009 mol Molarity = moles / volume (in L) Molarity = 0.0009009 mol / 0.100 L Molarity = 0.009009 M Next, we can calculate the van't Hoff factor (i): CaCl₂ dissolves into Ca2+ and Cl- ions, so i = 3 (2 for Ca2+ and 1 for Cl-). Now we can use the van't Hoff equation to calculate the osmotic pressure: π = iMRT π = 3 x 0.009009 M x 0.08206 L atm mol^-1 K^-1 x 298 K π = 0.658 atm Rounding to two significant figures gives an answer of 0.66 atm, which is choice C.

Calculate the Osmotic Pressure at 298 K of a Solution