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A solution of glucose (molar mass = 180 g/mol) in water is labelled as 10% (by mass). what would be the molality and molarity of the solution?
(density of solution = 1.2 g/mL)

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A solution of glucose in water is labelled as 10% by weight. What would be the molality of the solution? (Molar mass of glucose is 180gm per mole) ? 3 years ago Answers : (2) As we know that---- Molality = number of moles of solute/mass of solvent in Kg ……(1) Now we have to find number of moles and mass of solvent in Kg both mass of solute = mass of glucose /molar mass of glucose …..(2) Molar mass of glucose (C6H12O6) = 6*C + 12*H + 6*O = 6*12 + 12*1 + 6*16 =180 g /mol Putting the value back in equation (2) we get Number of moles = 10/180 = 0.0556 moles We have mass of solvent (H2O) = Mass of solution – Mass of solute = 100g- 10g = 90 g Mass in Kg = 90 g* 1 Kg / 1000 g = 0.09 Kg Putting the value in equation (1) we get Molality = 0.0556/0.09 = 16.7m

Find the molarity ,

molarity = number of moles of solute / volume of solution in liter ……….(1)

Volume = mass / density

= 100 g / 1.2 g/ ml = 83.33 ml

Mass in liter = 83.33 * 1 liter /1000 ml = 0.0833liter

Plug the value back equation (1) we get

Molarity = 0.0556/ 0.0833

= 0.67 M


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