Chapter 13, Problem 77GQ

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

A 2.0% (by mass) aqueous solution of novocainium chloride (C13H21ClN2O2) freezes at −0.237 °C. Calculate the van’t Hoff factor, i. How many moles of ions are in the solution per mole of compound?

Interpretation Introduction

Interpretation: van’t Hoff factor has to be calculated. The number of moles of ions produced in the solution per mole of compound 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

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

Freezing point depression = ΔTfp= Kfp. msolute.i,where,Kfp=molal freezing point depression constant,msolute= molality of solute,i=van'tHofffactor.

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.

Molality (m): Molality is the number of moles of solute present in one kilogram of solvent.

Molality (m) =Numberofmolesofsolute1kgofsolvent

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

Numberofmole=GivenmassofthesubstanceMolarmass

Explanation

Given,

â€‚Â Î”Tfpâ€‰=â€‰âˆ’0.2370Câ€‰Kfpâ€‰ofâ€‰waterâ€‰=â€‰âˆ’1.860C/m

â€‚Â Mass of novocainium chloride is 2100â€‰Ã—â€‰100â€‰gâ€‰=â€‰2â€‰g

â€‚Â Molar mass of novocainium chloride is 272.77â€‰g/mol

â€‚Â Mass of water is 100â€‰gâ€‰âˆ’â€‰2â€‰gâ€‰=â€‰98â€‰g

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

â€‚Â Numberâ€‰ofâ€‰moleâ€‰=Givenâ€‰massâ€‰ofâ€‰theâ€‰substanceMolarâ€‰massâ€‰=â€‰2â€‰g272.77â€‰g/mol=â€‰7.33â€‰Ã—â€‰10âˆ’3â€‰mol

Molality of the novocainium chloride solution is,

â€‚Â MolalityÂ (m)Â =Numberâ€‰ofâ€‰molesâ€‰ofâ€‰solute1kgâ€‰ofâ€‰solvent=â€‰7

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