Chapter 16- Organic Analysis

Question 1

What is the chemical test for alcohols?

Answer 1

Add acidified potassium dichromate which turns from orange to green with primary, secondary alcohols (or aldehydes)

Question 2

What is the chemical test for alkenes?

Answer 2

Bromine water turns from orange to colourless as bromine is added across C=C bond

Question 3

What are the chemical tests for aldehydes?

Answer 3

Tollens’ test- silver mirror forms
Fehling’s test- blue solution to red precipitate

Question 4

What is the chemical test for carboxylic acids?

Answer 4

Add NaHCO3 (aq) and CO2 is given off (bubble through limewater which will turn cloudy)

Question 5

What is the chemical test for haloalkanes?

Answer 5

Add NaOH (aq) and warm, acidify with nitric acid and add AgNO3 (aq). AgX precipitate will form with different colours.

Question 6

What is mass spectrometry?

Answer 6

A technique used to identify compounds and determine relative molecular mass

Question 7

What about bonds does infrared spectroscopy make use of?

Answer 7

The fact that different bonds absorb infrared radiation at characteristic wavenumbers (different frequencies)

Question 8

What is the fingerprint region?

Answer 8

The region on an IR spectrum below 1500 cm-1 which is unique to each molecule. A computer can be used to match the fingerprint region of a sample to those on a database of compounds.