[{"data":1,"prerenderedAt":-1},["ShallowReactive",2],{"detail-sidebar-cat-1-en-105":3,"doc-seo-572737-105":53,"doc-detail-572737-en":130},{"code":4,"msg":5,"data":6},0,"success",[7,14,19,24,29,34,39,44,49],{"id":8,"doc_module":9,"doc_module_name":10,"category_name":11,"show_sort_weight":12,"slug":13},11,1,"Template","Presentations",90,"presentations",{"id":15,"doc_module":9,"doc_module_name":10,"category_name":16,"show_sort_weight":17,"slug":18},12,"Resumes",80,"resumes",{"id":20,"doc_module":9,"doc_module_name":10,"category_name":21,"show_sort_weight":22,"slug":23},14,"Invoices",70,"invoices",{"id":25,"doc_module":9,"doc_module_name":10,"category_name":26,"show_sort_weight":27,"slug":28},15,"Posters",60,"posters",{"id":30,"doc_module":9,"doc_module_name":10,"category_name":31,"show_sort_weight":32,"slug":33},16,"Social Media",50,"social-media",{"id":35,"doc_module":9,"doc_module_name":10,"category_name":36,"show_sort_weight":37,"slug":38},17,"Forms",40,"forms",{"id":40,"doc_module":9,"doc_module_name":10,"category_name":41,"show_sort_weight":42,"slug":43},18,"Letters",30,"letters",{"id":45,"doc_module":9,"doc_module_name":10,"category_name":46,"show_sort_weight":47,"slug":48},21,"Paper Templates",5,"papers-templates",{"id":50,"doc_module":9,"doc_module_name":10,"category_name":51,"show_sort_weight":4,"slug":52},158,"General","general-158",{"code":4,"msg":54,"data":55},"ok",{"site_id":56,"language":57,"slug":58,"title":59,"keywords":60,"description":61,"schema_data":62,"social_meta":123,"head_meta":125,"extra_data":127,"updated_unix":129},105,"en","mass-and-infra-red-spectroscopy-mass-spectroscopy-interpreting-a-mass-spectrum-infra-red-spectroscopy","MASS and INFRA RED SPECTROSCOPY - Mass Spectroscopy - Interpreting a Mass Spectrum - Infra-red Spectroscopy","","Mass spectroscopy explains how molecules fragment into ions, producing fragmentation patterns that help identify organic compounds. It links the molecular ion peak at the highest m/z to relative molecular mass, then uses common fission examples (e.g., butanone) to infer plausible formulas that sum to the measured mass. Infra-red spectroscopy describes how bonds absorb specific frequencies, often expressed as wavenumbers (cm−1), and uses absorption ranges for functional groups. It also covers fingerprint regions, hydrogen bonding effects (broad O–H bands), and infrared uses in structure determination and confirming reactions, including cases in atmospheric gases.",{"@graph":63,"@context":122},[64,80,101],{"@type":65,"itemListElement":66},"BreadcrumbList",[67,71,74,77],{"item":68,"name":69,"@type":70,"position":9},"https://docshare.wps.com","Home","ListItem",{"item":72,"name":10,"@type":70,"position":73},"https://docshare.wps.com/template/",2,{"item":75,"name":51,"@type":70,"position":76},"https://docshare.wps.com/template/general/",3,{"item":78,"name":59,"@type":70,"position":79},"https://docshare.wps.com/template/mass-and-infra-red-spectroscopy-mass-spectroscopy-interpreting-a-mass-spectrum-infra-red-spectroscopy/572737/",4,{"url":78,"name":59,"@type":81,"image":82,"author":87,"headline":59,"publisher":90,"fileFormat":93,"inLanguage":57,"description":61,"dateModified":94,"datePublished":95,"encodingFormat":93,"isAccessibleForFree":96,"interactionStatistic":97},"DigitalDocument",{"url":83,"@type":84,"width":85,"height":86},"https://docshare.wps.com/thumbnails/mass-and-infra-red-spectroscopy-mass-spectroscopy-interpreting-a-mass-spectrum-infra-red-spectroscopy/572737.png","ImageObject",442,249,{"name":88,"@type":89},"Bintang","Person",{"url":68,"name":91,"@type":92},"DocShare","Organization","application/pdf","2026-10-21","2026-10-13",true,{"@type":98,"interactionType":99,"userInteractionCount":47},"InteractionCounter",{"@type":100},"ViewAction",{"@type":102,"mainEntity":103},"FAQPage",[104,110,114,118],{"name":105,"@type":106,"acceptedAnswer":107},"How does mass spectrometry help identify organic compounds?","Question",{"text":108,"@type":109},"Compounds fragment into positive ions, forming patterns that depend on molecular structure. These fragmentation patterns can be matched to expected features for identification.","Answer",{"name":111,"@type":106,"acceptedAnswer":112},"What does the molecular ion peak in a mass spectrum represent?",{"text":113,"@type":109},"The highest m/z peak is the molecular ion peak, and its mass gives the relative molecular mass of the molecule.",{"name":115,"@type":106,"acceptedAnswer":116},"How do infrared spectra indicate which bonds or functional groups are present?",{"text":117,"@type":109},"IR light is absorbed at frequencies that match bond vibrations. By comparing which frequencies are absorbed and using functional-group absorption ranges, the present bonds can be determined.",{"name":119,"@type":106,"acceptedAnswer":120},"What is the “fingerprint region” in IR spectroscopy?",{"text":121,"@type":109},"The fingerprint region is a part of the IR spectrum where the pattern becomes more complex but is characteristic for the same compound, enabling identification by matching patterns.","https://schema.org",{"og:url":78,"og:type":124,"og:title":59,"og:site_name":91,"og:description":61},"article",{"robots":126,"canonical":78},"index,follow",{"doc_id":128,"site_id":56},572737,1792109550,{"code":4,"msg":5,"data":131},{"doc_id":128,"user_id":132,"nickname":88,"user_avatar":133,"doc_module":9,"category_id":50,"category_name":51,"doc_title":59,"doc_description":61,"doc_content":134,"file_id":135,"file_url":136,"file_type":137,"file_size":138,"view_count":47,"is_deleted":4,"is_public":9,"is_downloadable":9,"audit_status":9,"page_count":139,"language":140,"language_code":57,"site_id":56,"html_lang":57,"table_of_contents":141,"faqs":142,"seo_title":143,"seo_description":61,"update_tm":144,"read_time":76},962085564381,"https://ap-avatar.wpscdn.com/davatar_6f874abed73319feea01a86fa6f0fab8","MASS and INFRA RED SPECTROSCOPY  \nMass Spectroscopy  \nThe mass spectrometer was looked at in Unit 1. It was noted there that compounds produce fragmentation patterns when passes through a mass spectrometer. These fragmentation patterns can be useful for identifying organic compounds.  \nThe C=O group for example tends to cause fragmentation each side of the C=O. The structures of propanal and propanone are shown below.  \nH O H  \nH ~~ ~~ C ~~ ~~ C ~~ ~~ C ~~ ~~ H  \nH H  \nH H  \nO  \nH ~~ ~~ C ~~ ~~ C ~~ ~~ C  \nH H  \nH  \nPropanone Propanal  \nIt is possible to deduce the pattern that might be obtained in a mass spectrograph by examining the likely fragmentation structures.  \nPropanone  \nH O H  \nH ~~ ~~ C ~~ ~~ C ~~ ~~ C ~~ ~~ H  \nH  \nH ~~ ~~ C  \nH  \n+ +  \nO H  \nC ~~ ~~ C ~~ ~~ H  \nH  \nLikely fragmentation Likely fragments at mass 15 and 43  \nis in one of these places  \nPropanal  \nLikely fragmentation Likely fragments at mass 29 and 58  \nis in one of these places  \nThe mass spectrographs for propanal and propanone produce the expected pattern.  \nPropanone  \nPropanal  \nInterpreting a Mass Spectrum  \nThe peak at highest mass/charge ratio is called the molecular ion peak and its mass will give the relative molecular mass of the molecule.  \nIn the spectrometer the molecules are fragmented into positive ions which form a pattern which depends on the structure of the molecule.  \ne.g. In butanone, CH 3 CH 2 COCH 3 fission to CH 3 CH 2 + (m/e=29) and CH 3 CO+ (m/e=43) is common.  \n• In this case the highest mass/charge ratio peak is at 72.  \n• Unless told otherwise, assume the molecule contains C, H, and probably O.  \n• Work out sensible possibilities which add up to 72, using C=12, H=1, O=16 .  \nHere is a systematic method:  \n• Start with the hydrocarbon with the maximum number of C atoms which add up to less than 72: – here, 5 C atoms (= 60), giving 12 Hs, and so C 5 H 12 . (C 6 and C4 H 24 are impossible) .  \n• Then add O atoms, removing CH4 (=16) each time: C4 H 8 O, C 3 H4 O 2 (can’t be C 2 O 3) .  \n• C4 H4 O has an RFM = 72.  \nInfra-red Spectroscopy  \nOrganic molecules absorb infra-red light. The reason for this is that the electromagnetic radiation in the infra-red region causes bonds to vibrate. Each bond vibrates at a particular frequency and absorbs the light at that frequency. T  \nhis means that by looking at which frequencies are absorbed, it is possible to determine which bonds are present.  \nIn infra-red spectroscopy a range of frequencies are passed through a compound and the intensity of the light emerging is detected. The infra-red spectrum shows the amount of light being absorbed at particular frequencies.  \nThe frequency is usually expressed as the wave number which is the reciprocal of the wavelength in units of cm-1 .  \nThe table below gives information about infrared absorption.  \n\n| Bond | Type of compound | Absorption | Intensity |\n| --- | --- | --- | --- |\n| C-H | Alkanes, alkenes, aldehydes | 2840 to 3095 | Medium-strong |\n| C=C | Alkenes | 1610 to 1680 | Medium |\n| C=O | Aldehydes and ketones | 1680 to 1750 | Strong |\n| (C-O) | (Alcohols) | 1000 to 1300 | Strong |\n| C-Cl |  | 700 to 800 | Strong |\n| O-H | “free” | 3850 to 3670 | Strong |\n|  | Hydrogen bonded in alcohols | 3230 to 3550 | Strong [Broad] |\n|  | Hydrogen bonded in carboxylic acids | 2500 to 3300 | Medium [Broad] |\n| N-H | amines | 3100 to 3500 | Strong |\n\nRanges of values are given because a functional group is affected by other functional groups nearby, so a particular bond will give one value in one compound and a slightly different one in another.  \nWhen looking at infrared spectrums, there will be a number of absorptions that we will not be able to recognize as we only study a selection of the possible absorptions.  \nThe infra-red spectrum for ethanal is shown below.  \nHydrogen bonded O-H stretch (broad)  \nC-O stretch  \nAt the right hand side of the spectrum, the peaks become more complicated, but since the same compound produces exactly the same p","cbCaih7FYBeX62Nf","https://ap.wps.com/l/cbCaih7FYBeX62Nf","pdf",102717,7,"English","# Mass Spectroscopy\n## Fragmentation patterns and identifying organic compounds\n## Interpreting a Mass Spectrum\n# Infra-red Spectroscopy\n## Principles of IR absorption and wavenumbers\n## Absorption ranges for bonds and functional groups\n## Fingerprint region and hydrogen bonding\n## Using IR with mass spectra to determine structure\n## IR evidence of chemical reactions\n# Absorption of Infra Red in the Atmosphere","[{\"question\":\"How does mass spectrometry help identify organic compounds?\",\"answer\":\"Compounds fragment into positive ions, forming patterns that depend on molecular structure. These fragmentation patterns can be matched to expected features for identification.\"},{\"question\":\"What does the molecular ion peak in a mass spectrum represent?\",\"answer\":\"The highest m/z peak is the molecular ion peak, and its mass gives the relative molecular mass of the molecule.\"},{\"question\":\"How do infrared spectra indicate which bonds or functional groups are present?\",\"answer\":\"IR light is absorbed at frequencies that match bond vibrations. By comparing which frequencies are absorbed and using functional-group absorption ranges, the present bonds can be determined.\"},{\"question\":\"What is the “fingerprint region” in IR spectroscopy?\",\"answer\":\"The fingerprint region is a part of the IR spectrum where the pattern becomes more complex but is characteristic for the same compound, enabling identification by matching patterns.\"}]","MASS and INFRA RED SPECTROSCOPY - Mass Spectroscopy - Interpreting a Mass Spectrum - Infra-red Spectroscopy | PDF",1791929073]