Structural ID Practice Problems
Table of Contents
Mass spectra on this page are taken from the NIST Chemistry WebBook.
Unknown 1
IR Spectrum
What functional groups might be present in this molecule?
Mass Spectrum
What is the A peak (molecular ion)?
How many C atoms are there in this molecule?
What does the nitrogen rule tell you about the molecule?
Can you come up with a formula?
Can you find evidence of a particular structure from the formula you determined?
| Ion [m/z] | Intensity [counts] | Intensity [%] |
|---|---|---|
| 15.0 | 90.0 | 0.2379 |
| 26.0 | 119.0 | 0.3146 |
| 27.0 | 2009.0 | 5.3110 |
| 28.0 | 389.0 | 1.0284 |
| 29.0 | 2739.0 | 7.2409 |
| 30.0 | 60.0 | 0.1586 |
| 37.0 | 10.0 | 0.0264 |
| 38.0 | 50.0 | 0.1322 |
| 39.0 | 1229.0 | 3.2490 |
| 40.0 | 209.0 | 0.5525 |
| 41.0 | 4379.0 | 11.5764 |
| 42.0 | 1529.0 | 4.0421 |
| 43.0 | 9999.0 | 26.4335 |
| 44.0 | 319.0 | 0.8433 |
| 50.0 | 40.0 | 0.1057 |
| 51.0 | 70.0 | 0.1851 |
| 52.0 | 30.0 | 0.0793 |
| 53.0 | 189.0 | 0.4996 |
| 54.0 | 80.0 | 0.2115 |
| 55.0 | 1139.0 | 3.0111 |
| 56.0 | 1839.0 | 4.8616 |
| 57.0 | 3349.0 | 8.8535 |
| 58.0 | 149.0 | 0.3939 |
| 62.0 | 10.0 | 0.0264 |
| 63.0 | 20.0 | 0.0529 |
| 65.0 | 20.0 | 0.0529 |
| 67.0 | 40.0 | 0.1057 |
| 68.0 | 10.0 | 0.0264 |
| 69.0 | 159.0 | 0.4203 |
| 70.0 | 1209.0 | 3.1961 |
| 71.0 | 2039.0 | 5.3903 |
| 72.0 | 99.0 | 0.2617 |
| 83.0 | 10.0 | 0.0264 |
| 84.0 | 709.0 | 1.8743 |
| 85.0 | 2649.0 | 7.0029 |
| 86.0 | 179.0 | 0.4732 |
| 114.0 | 599.0 | 1.5835 |
| 115.0 | 60.0 | 0.1586 |
Unknown 2
IR Spectrum
What functional groups might be present in this molecule?
Mass Spectrum
What is the A peak (molecular ion)?
How many C atoms are there in this molecule?
What does the nitrogen rule tell you about the molecule?
Can you come up with a formula?
Can you find evidence of a particular structure from the formula you determined?
| Ion [m/z] | Intensity [counts] | Intensity [%] |
|---|---|---|
| 14.0 | 10.0 | 0.0295 |
| 15.0 | 90.0 | 0.2654 |
| 25.0 | 10.0 | 0.0295 |
| 26.0 | 210.0 | 0.6193 |
| 27.0 | 1890.0 | 5.5741 |
| 28.0 | 280.0 | 0.8258 |
| 29.0 | 1360.0 | 4.0110 |
| 30.0 | 30.0 | 0.0885 |
| 37.0 | 80.0 | 0.2359 |
| 38.0 | 210.0 | 0.6193 |
| 39.0 | 1930.0 | 5.6920 |
| 40.0 | 320.0 | 0.9438 |
| 41.0 | 5759.0 | 16.9847 |
| 42.0 | 6119.0 | 18.0464 |
| 43.0 | 9999.0 | 29.4895 |
| 44.0 | 380.0 | 1.1207 |
| 49.0 | 20.0 | 0.0590 |
| 50.0 | 130.0 | 0.3834 |
| 51.0 | 160.0 | 0.4719 |
| 52.0 | 50.0 | 0.1475 |
| 53.0 | 210.0 | 0.6193 |
| 54.0 | 60.0 | 0.1770 |
| 55.0 | 540.0 | 1.5926 |
| 56.0 | 410.0 | 1.2092 |
| 57.0 | 1990.0 | 5.8690 |
| 58.0 | 90.0 | 0.2654 |
| 61.0 | 20.0 | 0.0590 |
| 62.0 | 30.0 | 0.0885 |
| 63.0 | 30.0 | 0.0885 |
| 65.0 | 20.0 | 0.0590 |
| 67.0 | 10.0 | 0.0295 |
| 69.0 | 10.0 | 0.0295 |
| 70.0 | 10.0 | 0.0295 |
| 71.0 | 80.0 | 0.2359 |
| 72.0 | 1290.0 | 3.8045 |
| 73.0 | 70.0 | 0.2064 |
Unknown 3
IR Spectrum
What functional groups might be present in this molecule?
Mass Spectrum
What is the A peak (molecular ion)?
How many C atoms are there in this molecule?
What does the nitrogen rule tell you about the molecule?
Can you come up with a formula?
Can you find evidence of a particular structure from the formula you determined?
| Ion [m/z] | Intensity [counts] | Intensity [%] |
|---|---|---|
| 15.0 | 60.0 | 0.1364 |
| 26.0 | 170.0 | 0.3866 |
| 27.0 | 1090.0 | 2.4786 |
| 28.0 | 350.0 | 0.7959 |
| 29.0 | 490.0 | 1.1142 |
| 30.0 | 10.0 | 0.0227 |
| 37.0 | 60.0 | 0.1364 |
| 38.0 | 190.0 | 0.4320 |
| 39.0 | 2380.0 | 5.4119 |
| 40.0 | 510.0 | 1.1597 |
| 41.0 | 5029.0 | 11.4355 |
| 42.0 | 2030.0 | 4.6160 |
| 43.0 | 930.0 | 2.1147 |
| 44.0 | 30.0 | 0.0682 |
| 49.0 | 30.0 | 0.0682 |
| 50.0 | 280.0 | 0.6367 |
| 51.0 | 410.0 | 0.9323 |
| 52.0 | 160.0 | 0.3638 |
| 53.0 | 640.0 | 1.4553 |
| 54.0 | 730.0 | 1.6600 |
| 55.0 | 3990.0 | 9.0729 |
| 56.0 | 9999.0 | 22.7369 |
| 57.0 | 480.0 | 1.0915 |
| 58.0 | 10.0 | 0.0227 |
| 61.0 | 10.0 | 0.0227 |
| 62.0 | 30.0 | 0.0682 |
| 63.0 | 70.0 | 0.1592 |
| 64.0 | 10.0 | 0.0227 |
| 65.0 | 140.0 | 0.3183 |
| 66.0 | 50.0 | 0.1137 |
| 67.0 | 400.0 | 0.9096 |
| 68.0 | 250.0 | 0.5685 |
| 69.0 | 3110.0 | 7.0719 |
| 70.0 | 180.0 | 0.4093 |
| 73.0 | 10.0 | 0.0227 |
| 74.0 | 30.0 | 0.0682 |
| 75.0 | 10.0 | 0.0227 |
| 77.0 | 120.0 | 0.2729 |
| 78.0 | 20.0 | 0.0455 |
| 79.0 | 90.0 | 0.2047 |
| 80.0 | 10.0 | 0.0227 |
| 81.0 | 50.0 | 0.1137 |
| 82.0 | 20.0 | 0.0455 |
| 83.0 | 510.0 | 1.1597 |
| 84.0 | 8209.0 | 18.6666 |
| 85.0 | 570.0 | 1.2961 |
| 86.0 | 20.0 | 0.0455 |
Unknown 4
IR Spectrum
What functional groups might be present in this molecule?
Mass Spectrum
What is the A peak (molecular ion)?
How many C atoms are there in this molecule?
What does the nitrogen rule tell you about the molecule?
Can you come up with a formula?
Can you find evidence of a particular structure from the formula you determined?
| Ion [m/z] | Intensity [counts] | Intensity [%] |
|---|---|---|
| 2.0 | 20.0 | 0.0594 |
| 12.0 | 60.0 | 0.1782 |
| 13.0 | 209.0 | 0.6207 |
| 14.0 | 489.0 | 1.4522 |
| 15.0 | 1709.0 | 5.0753 |
| 16.0 | 239.0 | 0.7098 |
| 17.0 | 99.0 | 0.2940 |
| 18.0 | 279.0 | 0.8286 |
| 24.0 | 20.0 | 0.0594 |
| 25.0 | 40.0 | 0.1188 |
| 26.0 | 50.0 | 0.1485 |
| 27.0 | 10.0 | 0.0297 |
| 28.0 | 409.0 | 1.2146 |
| 29.0 | 849.0 | 2.5213 |
| 30.0 | 40.0 | 0.1188 |
| 31.0 | 249.0 | 0.7395 |
| 32.0 | 10.0 | 0.0297 |
| 40.0 | 80.0 | 0.2376 |
| 41.0 | 359.0 | 1.0661 |
| 42.0 | 1309.0 | 3.8874 |
| 43.0 | 9999.0 | 29.6944 |
| 44.0 | 249.0 | 0.7395 |
| 45.0 | 9039.0 | 26.8435 |
| 46.0 | 109.0 | 0.3237 |
| 47.0 | 20.0 | 0.0594 |
| 55.0 | 10.0 | 0.0297 |
| 57.0 | 20.0 | 0.0594 |
| 60.0 | 7479.0 | 22.2107 |
| 61.0 | 199.0 | 0.5910 |
| 62.0 | 20.0 | 0.0594 |