   Chapter 13, Problem 66GQ

Chapter
Section
Textbook Problem

The smell of ripe raspberries is due to 4-(p-hydroxyphenyl)-2-butanone, which has the empirical formula C5H6O. To find its molecular formula, you dissolve 0.135 g in 25.0 g of chloroform, CHCl3. The boiling point of the solution is 61.82 °C. What is the molecular formula of the solute?

Interpretation Introduction

Interpretation: The molar mass and its molecular formula of 4-(p-hydroxyphenyl)-2-butanone is 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

Boiling point elevation: The boiling point of the solution varies with the solute concentration.

ΔTbp=Kbpmsolute

where,

Kbp is the molal boiling point elevation constant.

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

Numberofmole=GivenmassofthesubstanceMolarmass

Explanation

The molar mass and its molecular formula of 4-(p-hydroxyphenyl)-2-butanone is calculated.

Given,

ΔT=(61.820C61.700C)=0.120C

Mass of 4-(p-hydroxyphenyl)-2-butanone is 0.135g

Mass of chloroform is 25g=0.025kg

Molal boiling point elevation constant of chloroform is 3.630C/m

Change in boiling point is calculated by using the equation,

ΔTbp=Kbpmsolute

Hence,

The concentration is calculated by,

Concentration,msolute=ΔTbpKbp=(0.120C)(3.630C/m)=0.0331m

The amount of 4-(p-hydroxyphenyl)-2-butanone is,

(0.0331m1kg)(0.025kg)=8

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 