30 ml of ethyl alcohol dissolve in 100ml of aqueous solution density of solution is 0.94g/ml and density of water is 1g/ml . Calculate molarity, molality and mole fraction of solute and solvent.
Answers
Volume of C2H5OH = 30ml
Volume of solution = 100ml
Density of solution = 0.94g/ml
Density of water = 1g/ml
Mass of water = Density x volume = 1 x 70 = 70g
moles of water = 3.8 mol
Mass of solution = Volume x density = 100 x 0.94 = 94g
Mass of C2H5OH = Mass of solution - Mass of water = 94 - 70 = 24g
Moles of C2H5OH = 24/46 = 0.52 moles
Molarity = no. of moles of C2H5OH/Volume of solution in litres = 0.52/0.1 = 5.2
Molality = no. of moles of C2H5OH/Mass of solvent in kg = 0.52/0.07 = 7.42
Mole fraction of C2H5OH (Solute) = no. of moles of C2H5OH/(no. of moles of C2H5OH + no. of moles of water) = 0.52/(0.52+ 3.8) = 0.52/4.32 = 0.12
Mole fraction of water(Solvent) = no. of moles of water/(no. of moles of C2H5OH + no. of moles of water) = 3.8/(0.52 + 3.8) = 3.8/4.32 = 0.88