C16 - Organic Analysis

Question 1

How do you test for an alkene?

Answer 1

Shake with bromine water and will turn from orange to colourless if a C=C bond is present

Question 2

How do you test for an alcohol?

Answer 2

Add acidified potassium dichromate and will turn from orange to green for primary or secondary alcohols

Question 3

How do you test for aldehydes?

Answer 3

With Tollens or Fehling’s reagent which form a silver mirror or a red ppt respectively

Question 4

How do you test for a carboxylic acid?

Answer 4

Add sodium hydrogen carbonate and CO2 will form if positive

Question 5

What is the use of high resolution mass spectrometry?

Answer 5

High resolution mass spectrometry can determine the m/z of a peak to several decimal places. This can distinguish between compounds that have very similar relative molecular masses (Mr) but different empirical formulae

Question 6

What causes fragmentation in mass spectrometry?

Answer 6

Electron impact

Question 7

What is special about an -OH group in an infrared spectroscopy?

Answer 7

It has a very wide trough

Question 8

In infrared spectroscopy which is deeper a C=O bond or a C=C bond?

Answer 8

A C=O bond