Exploring Chemical Analysis
Exploring Chemical Analysis
5th Edition
ISBN: 9781429275033
Author: Daniel C. Harris
Publisher: Macmillan Higher Education
Question
Book Icon
Chapter 21, Problem 21.25P

(a)

Interpretation Introduction

Interpretation:

Plausible formula for CnHxOyNz has to be suggested when nominal mass is 79 and ratio of M++1/M+ peak is 5.9 %.

Concept Introduction:

Nominal mass may be defined as mass of most abundant isotope of a particular ion or molecule. For instance, carbon exist as two isotopes C-12 and C-13. C-12 is abundant as much as 98.9 % while abundance of C-13 is only 1.1 %. So clearly nominal mass of carbon is 12 g.

(a)

Expert Solution
Check Mark

Explanation of Solution

Odd nominal mass of 79 suggests there are odd numbers of N atoms. So it can be 1, 3 or any odd number.

Natural abundance of C-13 is 1.1 %. Hence number of C atoms is calculated as follows:

  M++1M+=n(1.1 %)n=5.9 %1.1 %=5.35

Hence number of C atom is 5.

Since each C has mass of 12, so five C atoms contribute a mass of 60 to overall formula CnHxOyNz. This leaves 19 mass that indicates possibility of one N atom and remainare five H atoms. So with no O atom, the plausible formula of compound is C5H5N.

(b)

Interpretation Introduction

Interpretation:

Plausible formula for CnHxOyNz has to be suggested when nominal mass is 123 and ratio of M++1/M+ peak is 6.1 %.

Concept Introduction:

Refer to part (a).

(b)

Expert Solution
Check Mark

Explanation of Solution

Odd nominal mass of 123 suggests there are odd numbers of N atoms. So it can be 1, 3 or any odd number.

Natural abundance of C-13 is 1.1 %. Hence number of C atoms is calculated as follows:

  M++1M+=n(1.1 %)n=6.1 %1.1 %=5.55 or 6

Hence number of C atom is 5 or 6.

Since each C has mass of 12 so six C atoms are assumed in formula then they contribute a mass of 72 to overall formula CnHxOyNz. This leaves 51 as mass that indicates possibility of only one N atom. If molecule has 3 N atoms then it would have contributed 41 and then no possibility of O atom exists.

With 1N, and 2 O and remainder 5 H atoms, contribution of 51 gets satisfied and thus one plausible formula is C6H5O2N.

When five C atoms are assumed in formula, they contribute a mass of 60 to overall formula CnHxOyNz. This leaves 63 as mass that indicates possibility of 3 N atoms and this would have contributed 42 and then one possibility of 1 O atom and remainder five H atoms. Thus, another possible formula is C5H5ON3.

(c)

Interpretation Introduction

Interpretation:

Plausible formula for CnHxOyNz has to be suggested when nominal mass is 148 and ratio of M++1/M+ peak is 7.4 %.

Concept Introduction:

Refer to part (a).

(c)

Expert Solution
Check Mark

Explanation of Solution

Even nominal mass of 148 suggests there are even numbers of N atoms. So it can be 2, 4 or any even number.

Natural abundance of C-13 is 1.1 %. Hence number of C atoms is calculated as follows:

  M++1M+=n(1.1 %)n=7.4 %1.1 %=6.77 or 6

Hence number of C atom is 7 or 6.

Plausible formulas with 6 C atoms that satisfy nominal mass of 148 include C6H12O4 and C6H16O2N2.

Plausible formulas with 7 C atoms that satisfy nominal mass of 148 include C7H4O2N2 and C7O4.

(d)

Interpretation Introduction

Interpretation:

Plausible formula for CnHxOyNz has to be suggested when nominal mass is 168 and ratio of M++1/M+ peak is 12.5 %.

Concept Introduction:

Refer to part (a).

(d)

Expert Solution
Check Mark

Explanation of Solution

Even nominal mass of 168 suggests there are even numbers of N atoms. So it can be 2, 4 or any even number.

Natural abundance of C-13 is 1.1 %. Hence number of C atoms is calculated as follows:

  M++1M+=n(1.1 %)n=12.5 %1.1 %=11.3611 or 12

Hence number of C atom is 11 or 12.

Plausible formulas with 11 C atoms that satisfy nominal mass of 168 includes C11H20O, C11H4O2 or C11H8N2.

Plausible formulas with 12 C atoms that satisfy nominal mass of 168 include C12H24 and C12H8O.

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
Draw a mental model for calcium chloride mixed with sodium phosphate
here is my question (problem number 20) please explain to me thanks!
The bromination of anisole is an extremely fast reaction. Complete the resonance structures of the intermediate arenium cation for the reaction (Part 1), and then answer the question that follows (Part 2).
Knowledge Booster
Background pattern image
Similar questions
SEE MORE QUESTIONS
Recommended textbooks for you
Text book image
Chemistry
Chemistry
ISBN:9781305957404
Author:Steven S. Zumdahl, Susan A. Zumdahl, Donald J. DeCoste
Publisher:Cengage Learning
Text book image
Chemistry
Chemistry
ISBN:9781259911156
Author:Raymond Chang Dr., Jason Overby Professor
Publisher:McGraw-Hill Education
Text book image
Principles of Instrumental Analysis
Chemistry
ISBN:9781305577213
Author:Douglas A. Skoog, F. James Holler, Stanley R. Crouch
Publisher:Cengage Learning
Text book image
Organic Chemistry
Chemistry
ISBN:9780078021558
Author:Janice Gorzynski Smith Dr.
Publisher:McGraw-Hill Education
Text book image
Chemistry: Principles and Reactions
Chemistry
ISBN:9781305079373
Author:William L. Masterton, Cecile N. Hurley
Publisher:Cengage Learning
Text book image
Elementary Principles of Chemical Processes, Bind...
Chemistry
ISBN:9781118431221
Author:Richard M. Felder, Ronald W. Rousseau, Lisa G. Bullard
Publisher:WILEY