Problem: A solution contains 3.75 g of a nonvolatile pure hydrocarbon in 95 g acetone. The boiling points of pure acetone and the solution are 55.95°C and 56.50°C, respectively. The molal boiling point constant of acetone is 1.71 °C • kg/mol. What is the molar mass of the hydrocarbon?

FREE Expert Solution

Boiling point elevation is a colligative property that describes the increase of the boiling point of a solution when a solute is added to a pure solvent. The mathematical equation for boiling point elevation is:



To solve for the molar mass of the hydrocarbon, we will:

  1. Solve for the molality of the solution
  2. Determine the mass in kg of the solvent
  3. Calculate the molar mass of the hydrocarbon


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Problem Details

A solution contains 3.75 g of a nonvolatile pure hydrocarbon in 95 g acetone. The boiling points of pure acetone and the solution are 55.95°C and 56.50°C, respectively. The molal boiling point constant of acetone is 1.71 °C • kg/mol. What is the molar mass of the hydrocarbon?

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What scientific concept do you need to know in order to solve this problem?

Our tutors have indicated that to solve this problem you will need to apply the The Colligative Properties concept. You can view video lessons to learn The Colligative Properties. Or if you need more The Colligative Properties practice, you can also practice The Colligative Properties practice problems.

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Our data indicates that this problem or a close variation was asked in Chemistry: An Atoms First Approach - Zumdahl Atoms 1st 2nd Edition. You can also practice Chemistry: An Atoms First Approach - Zumdahl Atoms 1st 2nd Edition practice problems.