Turn on thread page Beta
    • Thread Starter

    hi im stuck on using mass spectroscopy to identify halogen compounds using [M+2] and [M+4] peaks, basicaly i dont understand where do there peaks come from and how do they help us identify compounds

    Thanks alot

    • Community Assistant
    • Study Helper

    Community Assistant
    Study Helper
    fact - chlorine has two isotopes 35-Cl and 37-Cl

    fact - the natural ratio of these two isotopes is 3:1

    any compound contianing chlorine will have peaks for molecules that contain each isotope. eg CH3Cl will have a peak at m/e = 50 and m/e = 52 corresponding to the molecules containing the 35 and 37 isotope respectively.

    If a molecule contains two chlorines eg CH2Cl2 then you would expect peaks corresponding to m/e = 84, 86 and 88 - the first having two 35-Cl isotopes, the second having one 35Cl and one 37Cl and the third containing two 37-Cl isotopes.

    see http://www.ibchem.com/IB/ibnotes/full/ato_htm/12.1.htm
Submit reply
Turn on thread page Beta
Updated: February 2, 2006

University open days

  • Southampton Solent University
    All faculties Undergraduate
    Sun, 18 Nov '18
  • University of Bradford
    All faculties Undergraduate
    Wed, 21 Nov '18
  • Buckinghamshire New University
    All Faculties Postgraduate
    Wed, 21 Nov '18
Black Friday: Yay or Nay?

The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE

Write a reply...
Reputation gems: You get these gems as you gain rep from other members for making good contributions and giving helpful advice.