Answered

Explore IDNLearn.com to discover insightful answers from experts and enthusiasts alike. Ask your questions and receive reliable, detailed answers from our dedicated community of experts.

A solution made by dissolving 9.81 g of a nonvolatile, nonelectrolyte in 90.0 g of water boiled at 100.37 °C at 760 mm Hg. What is the molar mass of the substance? [kp = 0.51 °c/m]

Sagot :

Maacastrobridn

Answer:

151 g/mol

Explanation:

In order to solve this problem we need to keep in mind the formula for the boiling point elevation:

  • ΔT = Kb * m * i

Where:

  • ΔT is the temperature difference between the boiling point of the solution and that of pure water. 100.37 °C - 100.00 °C = 0.37 °C.
  • m is the molarity of the solution
  • i is the van't Hoff factor. As the solute is a nonelectrolyte, the factor is 1.

Input the data and calculate m:

  • 0.37 °C = 0.51 °C/m * m * 1
  • m =0.72 m

We now can calculate the number of moles of the substance, using the definition of molarity:

  • molarity = moles of solute / kg of solvent

In this case kg of solvent = 90.0 g / 1000 = 0.090 kg

  • 0.72 m = moles / 0.090 kg
  • moles = 0.065 mol

Finally we calculate the molar mass, using the number of moles and the mass:

  • 9.81 g / 0.065 mol = 151 g/mol
Thank you for contributing to our discussion. Don't forget to check back for new answers. Keep asking, answering, and sharing useful information. Thanks for visiting IDNLearn.com. We’re dedicated to providing clear answers, so visit us again for more helpful information.