An antifreeze solution is prepared from 222.6 g of ethylene glycol (C2H6O2) and 200 g of water. Calculate the molality of the solution. If the density of the solution is 1.072 g mL−1, then what shall be the molarity of the solution?
Answers
Answer:
An antifreeze solution is prepared from 222.6 g of ethylene glycol (C2H6O2) and 200 g of water. Calculate the molality of the solution. If the density of the solution is 1.072 g mL−1, then what shall be the molarity of the solution?
Molality of the solution is 17.592 moles/kg
Molarity of the solution is 9.12 M
Explanation:
Molality
Formula for calculating Molality is:
Molality = Moles of solute / kilograms of solvent
Solute is Ethylene glycol while the solvent is water.
⇒Moles of Ethylene glycol:
Moles = mass / molar mass
Mass of Ethylene glycol = 222.6 g
Molar mass of Ethylene glycol (C₂H₆O₂) = 24 + 6 + 32 = 62
Moles of Ethylene glycol (C₂H₆O₂) = 222.6 / 62 = 3.59 moles
⇒ Mass of water as the solvent in kilograms = 200 g
200 g in kg = 200/1000 = 0.2 kg
∴ Molality = 3.59 moles / 0.2kg
= 17.592 moles/kg
Molarity
Formula for molarity is:
Molarity = Moles of solute / volume of solution in liters
Moles of the Ethylene glycol = 3.59 moles
Volume of the solution.
The denisty of the solution is 1.072 g/ml
The mass of the solution is 222.6 + 200 = 422.6g
Therefore the volume of the solution will be:
If 1.072 g = 1 ml
Then 422.6g = 1 ml × 422.6g/1.072g
= 394.23 ml
Convert 394.23 ml to liters using 1000ml = I liter conversion factor
This means that 394.23 ml = 394.23 ml/1000 Litres
= 0.39423 litres
Molarity = 3.59 moles / 0.39423 litres
= 9.12 M
Explanation:
Molecular mass of glycol C2H4(OH)2 =62
Number of moles of C2H4(OH)2 = mass of glycol / molar mass of glycol
= 222.6/62=3.59 moles
Molality of solution = number of moles of solute / mass of solvent in Kg
Mass of solvent = 200g = 200/1000 Kg = 0.2 kg
Plug the values we get
Molality = 3.59/0.2
Molality = 17.95
Formula of molarity of solution = number of moles of solute / volume of solution in Kg
Formula of volume = mass / density
Volume = 422.6g/(1.072 g/ml)
Volume = 394.21 ml
Convert in liter
Volume in liter = 394.21 ml /1000 liter =0.394 liter