question_answer 5)

Calculate (a) molarity (b) molarity and (c) mole fraction of KI if the density of 20% (mass/mass) aqueous KI is 1.202 g mL–1.

Answer:

20% (mass/mass) aqueous KI solution means that 20 g of KI is present in 100 g solution. Mass of KI = 20 g Mass of aqueous solution = 100 g Mass of solvent (water) = 100 g - 20 g = 80 g = 0.080 kg (a) Calculation of molality Molar mass of KI = 39 + 127 = 166 g mol-1 Molality of solution   (b) Calculation of molarity Density of solution = 1.202 g mL-1  Volume of solution   83.2 mL = 0.0832 L Molarity of solution   (c) Calculation of mole fraction of KI No. of moles of KI(nKI) = 20g/166 g mol-1 = 0.120 moles No. of moles of water (nH2O) = 4.44 Mole fraction of