Laboratory Techniques in Organic Chemistry
Laboratory Techniques in Organic Chemistry
4th Edition
ISBN: 9781464134227
Author: Jerry R. Mohrig, David Alberg, Gretchen Hofmeister, Paul F. Schatz, Christina Noring Hammond
Publisher: W. H. Freeman
Question
Book Icon
Chapter 12, Problem 1Q
Interpretation Introduction

Interpretation:

The reason for the observed boiling point for the first drop of the collected distillate of pentane and hexane to be higher than the boiling point of pentane should be determined.

Concept introduction:

Distillation is a liquid-gas separation technique for two or more liquids on the basis of their difference in boiling point or vapor pressure.

Vapor pressure is pressure exerted by vapor phase of liquid produced due to an increase in the molecular kinetic energy of the liquid phase or due to the increase in temperature.

The temperature at which atmospheric pressure exerted on liquid equals to its vapor pressure is known to be its boiling point. Vapor pressure of the component decide boiling point of any mixture. Impurities in the mixture might result in an increase or decrease of observed boiling point.

Expert Solution & Answer
Check Mark

Explanation of Solution

Hexane and pentane are mutually soluble in each other and their solution boil at a temperature intermediate of their boiling point.

In case of pentane and hexane that have 1:1 molarity, the boiling point that is noticed for the first drop of collected distillate is above boiling point of pentane because pentane has lower boiling temperature than that of hexane. Therefore, when the sample is heated for distillation then pentane will first vaporize, and vapor phase will be rich in pentane so it will exert more vapor pressure initially.

The first drop of the distillate obtained will have a higher boiling point than the pentane as hexane that is present in the mixture will act as impurity and will lead to an increase in its observed boiling point.

Want to see more full solutions like this?

Subscribe now to access step-by-step solutions to millions of textbook problems written by subject matter experts!
Students have asked these similar questions
Why is flameless heating used for heating a solution in hexane or diethyl ether during a recrystallization?   Why should the size of crystals obtained in a recrystallization be neither too large nor too small?
Impure acetanilide was dissolved in hot water. The solution was filtered hot and the beaker of solution was immediately placed in an ice-water bath instead being allowed to cool slowly. What will be the result of cooling the solution in this manner?
explain why the boiling point of a two component mixture rises slowly throughout a simple distillation when the boiling-point differences are not larger
Knowledge Booster
Background pattern image
Similar questions
SEE MORE QUESTIONS
Recommended textbooks for you
Text book image
EBK A SMALL SCALE APPROACH TO ORGANIC L
Chemistry
ISBN:9781305446021
Author:Lampman
Publisher:CENGAGE LEARNING - CONSIGNMENT
Text book image
Macroscale and Microscale Organic Experiments
Chemistry
ISBN:9781305577190
Author:Kenneth L. Williamson, Katherine M. Masters
Publisher:Brooks Cole