Chapter 13, Problem 45PS

### Chemistry & Chemical Reactivity

10th Edition
John C. Kotz + 3 others
ISBN: 9781337399074

Chapter
Section

### Chemistry & Chemical Reactivity

10th Edition
John C. Kotz + 3 others
ISBN: 9781337399074
Textbook Problem

# An aqueous solution contains 0.180 g of an unknown, nonionic solute in 50.0 g of water. The solution freezes at −0.040 °C. What is the molar mass of the solute?

Interpretation Introduction

Interpretation: The molar mass of unknown nonionic solute has to be determined.

Concept introduction:

Colligative properties: Properties of solutions which having influence on the concentration of the solute in it. Colligative properties are,

• Decrease in the vapor pressure
• Increase in the boiling point
• Decline in the freezing point
• Osmotic pressure

Change in freezing point is calculated by using the equation,

ΔTfp=Kfpmsolute

where,

Kfp is the molal freezing point depression constant.

The number of moles of any substance can be determined using the equation

Numberofmole=GivenmassofthesubstanceMolarmass

Explanation

The molar mass of unknown nonionic solute is calculated.

Given,

â€‚Â Î”Tâ€‰=â€‰âˆ’0.0400C

â€‚Â Mass of unknown nonionic solute is 0.180â€‰g

â€‚Â Mass of water is 50â€‰gâ€‰=â€‰0.050â€‰kg

â€‚Â Molal freezing point depression constant of water is â€‰âˆ’1.860C/m

Change in freezing point is calculated by using the equation,

â€‚Â Î”Tfpâ€‰=â€‰Kfpâ€‰msolute

Hence,

The concentration is calculated by,

â€‚Â Concentration,msolute=â€‰Î”TfpKfp=â€‰(â€‰âˆ’0.0400C)(âˆ’1.860C/m)=â€‰0.0215â€‰m

The amount of unknown nonionic solute is,

â€‚Â (â€‰0

### Still sussing out bartleby?

Check out a sample textbook solution.

See a sample solution

#### The Solution to Your Study Problems

Bartleby provides explanations to thousands of textbook problems written by our experts, many with advanced degrees!

Get Started