Answered

Welcome to Westonci.ca, where finding answers to your questions is made simple by our community of experts. Discover the answers you need from a community of experts ready to help you with their knowledge and experience in various fields. Explore comprehensive solutions to your questions from knowledgeable professionals across various fields on our platform.

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 :

maacastrobr

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
We hope this was helpful. Please come back whenever you need more information or answers to your queries. Thanks for stopping by. We strive to provide the best answers for all your questions. See you again soon. We're dedicated to helping you find the answers you need at Westonci.ca. Don't hesitate to return for more.