3.6 Organic Analysis Flashcards
Give the definition of a molecular ion.
A molecular ion is the molecule with one electron knocked off (it is both and ion and a free radical)
What can be used to determine the molecular formula of a compound?
High resolution mass spectrometry can be used to determine the molecular formula of a compound from the accurate mass of the molecular ion.
To what decimal place can high resolution mass spectrometry measure mass to?
5 d.p.
This can help differentiate between compounds that appear to have similar Mr (to the nearest whole number)
Answer the example question 1 on page 1 in the chemrevise revision guide.
correct?
How many molecular ion peaks will occur if a compound contains a chlorine or a bromine atom?
What type of peaks?
Why?
2 peaks
a M and a M+2 peak
Due to the two naturally occurring isotopes of chlorine or bromine.
What are the two naturally occurring isotopes of chlorine?
Cl35 (75%)
Cl37 (25%)
What are the two naturally occurring isotopes of bromine?
Br79 (50%)
Br81 (50%)
What will the m/z value be for CH3Cl35 and CH3Cl37?
What will the ratio of heights be?
CH3Cl35 - 50
CH3Cl37 - 52
3:1
(see page 1 in the chemrevise revision guide)
What will the m/z value be for CH3Br79 and CH3Br81?
CH3Br79 - 94
CH3Br81 - 96
1:1
(see page 1 in the chemrevise revision guide)
Read the box labelled 1 on page 1 in the chemrevise revision guide.
understand?
Read the box labelled 1 on page 2 in the chemrevise revision guide.
understand?
In an infrared spectra, what is the information above 1500cm-1 and what is the information below 1500cm-1?
Above - functional group identification
Below - fingerprinting
Look at the graph in on page 2 in the chemrevise revision guide, give the two functional groups shown there using the IR absorption table below.
answer is below table, correct?
need to do work on infrared spectroscopy
feel confident you know it?
Read the top of page 3 in the chemrevise revision guide
understand?
In a test tube reaction, what reagent is used to test for alkenes?
What is the result if positive?
Bromine water
Orange colour -> colourless
In a test tube reaction, what reagent is used to test for aldehydes?
What is another reagent used?
What is the result if positive?
Fehling’s solution
Blue solution -> red precipitate
Tollen’s reagent
Silver mirror formed
In a test tube reaction, what reagent is used to test for Carboxylic acids?
What is the result if positive?
Sodium carbonate
Effervescence of CO2 evolved
In a test tube reaction, what reagent is used to test for 1º 2º alcohol and aldehyde?
What is the result if positive?
Sodium dichromate and sulfuric acid
Orange -> green
In a test tube reaction, what reagent is used to test for chloroalkanes?
What is the result if positive?
Warm with silver nitrate
Slow formation of white precipitate of AgCl
For Tollen’s reagent with aldehydes:
How is the reagent formed?
What are the conditions?
What is the reaction?
What are the observations?
(see page 3 in the chemrevise revision guide)
For Fehling’s solution with aldehydes:
What is the reagent?
What are the conditions?
What is the reaction?
What are the observations?
(see page 3 in the chemrevise revision guide)
Draw an equation for the test for the presence of a carboxylic acid.
(see page 3 in the chemrevise revision guide)
