Chapter 13.4, Problem 13.10CYU

### 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

# Calculate the freezing point of 525 g of water that contains 25.0 g of NaCl. Assume i, the van’t Hoff factor, is 1.85 for NaCl.

Interpretation Introduction

Interpretation: The calculated freezing point of the NaCl solution has to be identified.

Concept introduction:

van’t Hoff factor, i: it is the ration between change in in freezing point measured and change in in freezing point calculated. It indicates the total number of ions that are produced.

van'tHofffactor,i=measuredΔTfpCalculatedΔTfp

Freezing point depression: The freezing point of the solution varies with the solute concentration.

ΔTfp=Kfpmsolute

where,

Kfp is the molal freezing point depression constant.

Explanation

Given data:

i=â€‰1.85Massâ€‰ofâ€‰waterâ€‰(solvent)â€‰=â€‰â€‰525â€‰gâ€‰â€‰=â€‰â€‰0.525kgMassâ€‰ofâ€‰soluteâ€‰(NaCl)â€‰â€‰=â€‰â€‰25.0â€‰gKfp(solventâ€‰water)Â Â =Â -1.86oC/m

Molality can be calculated using the equation:

MolalityÂ =Â Moleâ€‰ofâ€‰soluteâ€‰(inâ€‰mol)Amountâ€‰ofâ€‰solventâ€‰(inâ€‰Kg)

MolalityÂ =Â Moleâ€‰ofâ€‰soluteâ€‰(inâ€‰mol)Amountâ€‰ofâ€‰solventâ€‰(inâ€‰kg)=â€‰(25.0â€‰g/58.4g.mol-1)0.525kgâ€‰=â€‰â€‰0.815â€‰m

Calculation of freezing point:

Î”TfpÂ measuredÂ =â€‰Â Kfp.â€‰msolute=â€‰(â€‰-1.86oC/m)(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