14. Shown below are the mass spectra (without data tables) of four molecules. (The structure of each molecule is shown on the spectrum.) Mark the [M]* peak for each, and indicate the molecular weight of the molecule. Relative Intensity 100- 20 0-fmrtn 10 100- 8 8 $ & 0- a. 10 b. 20 20 30 40 50 60 m/z m/z 70 80 90 100 100 100- Relative Intensity 80 Relative Intensity 8 20 100- 8 8 9 20 10 15 20 25 30 e 0- -8 35 40 45 50 55 60 65 70 m/z m/z Based on the five mass spectra you have seen, describe how one might identify the [M]* peak (molecular ion peak) on the mass spectrum of an unknown compound.
14. Shown below are the mass spectra (without data tables) of four molecules. (The structure of each molecule is shown on the spectrum.) Mark the [M]* peak for each, and indicate the molecular weight of the molecule. Relative Intensity 100- 20 0-fmrtn 10 100- 8 8 $ & 0- a. 10 b. 20 20 30 40 50 60 m/z m/z 70 80 90 100 100 100- Relative Intensity 80 Relative Intensity 8 20 100- 8 8 9 20 10 15 20 25 30 e 0- -8 35 40 45 50 55 60 65 70 m/z m/z Based on the five mass spectra you have seen, describe how one might identify the [M]* peak (molecular ion peak) on the mass spectrum of an unknown compound.
Chemistry
10th Edition
ISBN:9781305957404
Author:Steven S. Zumdahl, Susan A. Zumdahl, Donald J. DeCoste
Publisher:Steven S. Zumdahl, Susan A. Zumdahl, Donald J. DeCoste
Chapter1: Chemical Foundations
Section: Chapter Questions
Problem 1RQ: Define and explain the differences between the following terms. a. law and theory b. theory and...
Related questions
Question
![**14. Shown below are the mass spectra (without data tables) of four molecules. (The structure of each molecule is shown on the spectrum.)**
**a. Mark the [M]^+ peak for each, and indicate the molecular weight of the molecule.**
There are four mass spectra, each with a chemical structure displayed in the top left corner. The x-axis of each spectrum is labeled "m/z" (mass-to-charge ratio), and the y-axis is labeled "Relative Intensity."
1. **First Spectrum (Top Left)**
- Structure: A hexagon (benzene ring).
- Main peak (likely [M]^+ peak) around 78 m/z.
- Additional peaks at lower m/z values.
2. **Second Spectrum (Top Right)**
- Structure: A ketone group (R-C=O).
- Main peak around 58 m/z.
- Additional peaks at lower m/z values.
3. **Third Spectrum (Bottom Left)**
- Structure: Cyclohexanone (hexane ring with a ketone group).
- Main peak around 98 m/z.
- Additional peaks at lower m/z values.
4. **Fourth Spectrum (Bottom Right)**
- Structure: An aliphatic chain.
- Main peak around 72 m/z.
- Additional peaks at lower m/z values.
**b. Based on the five mass spectra you have seen, describe how one might identify the [M]^+ peak (molecular ion peak) on the mass spectrum of an unknown compound.**
To identify the [M]^+ peak on a mass spectrum of an unknown compound, look for the peak with the highest m/z value that also possesses significant relative intensity. This peak generally corresponds to the molecular weight of the intact molecule. Fragment ion peaks are typically observed at lower m/z values and help in determining the structure by indicating possible fragmentation patterns of the molecule.](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2Fa1871893-1489-414f-ba40-94b584c7772f%2F2910ade3-8d67-4703-b310-6816fc7ff8fa%2Flw4t4et_processed.png&w=3840&q=75)
Transcribed Image Text:**14. Shown below are the mass spectra (without data tables) of four molecules. (The structure of each molecule is shown on the spectrum.)**
**a. Mark the [M]^+ peak for each, and indicate the molecular weight of the molecule.**
There are four mass spectra, each with a chemical structure displayed in the top left corner. The x-axis of each spectrum is labeled "m/z" (mass-to-charge ratio), and the y-axis is labeled "Relative Intensity."
1. **First Spectrum (Top Left)**
- Structure: A hexagon (benzene ring).
- Main peak (likely [M]^+ peak) around 78 m/z.
- Additional peaks at lower m/z values.
2. **Second Spectrum (Top Right)**
- Structure: A ketone group (R-C=O).
- Main peak around 58 m/z.
- Additional peaks at lower m/z values.
3. **Third Spectrum (Bottom Left)**
- Structure: Cyclohexanone (hexane ring with a ketone group).
- Main peak around 98 m/z.
- Additional peaks at lower m/z values.
4. **Fourth Spectrum (Bottom Right)**
- Structure: An aliphatic chain.
- Main peak around 72 m/z.
- Additional peaks at lower m/z values.
**b. Based on the five mass spectra you have seen, describe how one might identify the [M]^+ peak (molecular ion peak) on the mass spectrum of an unknown compound.**
To identify the [M]^+ peak on a mass spectrum of an unknown compound, look for the peak with the highest m/z value that also possesses significant relative intensity. This peak generally corresponds to the molecular weight of the intact molecule. Fragment ion peaks are typically observed at lower m/z values and help in determining the structure by indicating possible fragmentation patterns of the molecule.
Transcribed Image Text:The **mass spectrum** of acetone is a tally of the number of ions of each mass (m/z) that hit the detector when a large number of acetone molecules are run through the mass spectrometer. The **peak intensity** (peak height) tells you the relative number of ions of that weight that hit the detector.
### Data Table
| m/z | Peak Intensity |
|------|----------------|
| 14.0 | 2.9 |
| 15.0 | 23.1 |
| 26.0 | 3.5 |
| 27.0 | 5.7 |
| 29.0 | 3.1 |
| 38.0 | 2.2 |
| 39.0 | 4.2 |
| 41.0 | 2.0 |
| 42.0 | 9.1 |
| 43.0 | 100.0 |
| 44.0 | 3.4 |
| 58.0 | 63.8 |
| 59.0 | 3.1 |
### Graph Description
The graph displays the mass spectrum of acetone, plotting m/z (mass-to-charge ratio) on the x-axis against relative intensity on the y-axis. Each vertical line (or peak) represents a different ion detected by the spectrometer.
- The tallest peak occurs at m/z 43.0 with 100.0 intensity, showing it's the most abundant ion.
- Another significant peak is at m/z 58.0 with an intensity of 63.8.
- Other smaller peaks are visible at m/z values of 15.0, 27.0, and 42.0, among others, indicating various ion fragments of acetone.
These peaks help in identifying the composition and structure of acetone molecules.
Expert Solution
This question has been solved!
Explore an expertly crafted, step-by-step solution for a thorough understanding of key concepts.
This is a popular solution!
Trending now
This is a popular solution!
Step by step
Solved in 2 steps with 1 images
Knowledge Booster
Learn more about
Need a deep-dive on the concept behind this application? Look no further. Learn more about this topic, chemistry and related others by exploring similar questions and additional content below.Recommended textbooks for you
Chemistry
Chemistry
ISBN:
9781305957404
Author:
Steven S. Zumdahl, Susan A. Zumdahl, Donald J. DeCoste
Publisher:
Cengage Learning
Chemistry
Chemistry
ISBN:
9781259911156
Author:
Raymond Chang Dr., Jason Overby Professor
Publisher:
McGraw-Hill Education
Principles of Instrumental Analysis
Chemistry
ISBN:
9781305577213
Author:
Douglas A. Skoog, F. James Holler, Stanley R. Crouch
Publisher:
Cengage Learning
Chemistry
Chemistry
ISBN:
9781305957404
Author:
Steven S. Zumdahl, Susan A. Zumdahl, Donald J. DeCoste
Publisher:
Cengage Learning
Chemistry
Chemistry
ISBN:
9781259911156
Author:
Raymond Chang Dr., Jason Overby Professor
Publisher:
McGraw-Hill Education
Principles of Instrumental Analysis
Chemistry
ISBN:
9781305577213
Author:
Douglas A. Skoog, F. James Holler, Stanley R. Crouch
Publisher:
Cengage Learning
Organic Chemistry
Chemistry
ISBN:
9780078021558
Author:
Janice Gorzynski Smith Dr.
Publisher:
McGraw-Hill Education
Chemistry: Principles and Reactions
Chemistry
ISBN:
9781305079373
Author:
William L. Masterton, Cecile N. Hurley
Publisher:
Cengage Learning
Elementary Principles of Chemical Processes, Bind…
Chemistry
ISBN:
9781118431221
Author:
Richard M. Felder, Ronald W. Rousseau, Lisa G. Bullard
Publisher:
WILEY