Question

Calculate molarity of a solution of ethanol in water in which the mole fraction of ethanol is 0.040

Answer 1

Mole fraction of C2H5OH= .................1Let the moles of C2H5OH= XNow density of water = 1 (given)And the weight of 1000ml of water = volume * density (from density = mass/volume)= 1000 x 1=1000gTherefore moles of water = 1000/18= 55.55 mol (18g is molecular mass of water)Also mole fraction of C2H5OH= 0.040 (given)Putting the values in equation 1,we get=0.040=X/X+55.55=0.040X+2.222 = XOR X= 2.3145 molMolarity of solution = 2.314 M