A solution of glucose in water is labelled as 10% w/w, what would be the molality and mole fraction of each component in the solution? If the density of solution is 1.2 g mL⁻¹, then what shall be the molarity of the solution?
Answers
What is Molality?
Concentration of a solute in solvent is often measured in terms of molarity and molality.
Molarity is denoted as 'M' and it is the moles of solute per litre of solution.
Molarity is usually applied in working with stoichiometric calculations involving solutions.
Molality is abbreviated as 'm' and is moles of solute per kilogram of solvent.What is Molarity?: Molarity (M) is the concentration of a solution denoted as the number of moles of solute per litre of solution:
Solution of the problem is given below:10%w/w solution of glucose in water means 10 g of glucose present in 100g of solution.
Therefore, Mass of glucose is 10g.Mass of water is = 100g- 10g = 90 g = 0.09 kg.And density = 1.2gmL-1Let us find molality.Molality = Number of moles of solute / Mass of solvent in Kg.
Number of moles of solute = Mass of glucose / Molar mass of glucose .
Molar mass of glucose (C6H12O6) = 6x12 + 12x1 + 6x16 =180 g /mol.
Number of moles of glucose = 10/180 = 0.0556 moles.
Molality = 0.0556/0.09 = 16.7M
Now find the molarity.
Molarity = Number of moles of solute / Volume of solution in liter.Density = 1.2 g/ml:Volume = mass / density = 100 g / 1.2 g/ ml = 83.33 ml = 0.0833 L:
Molarity = 0.0556/ 0.0833= 0.67 M