Organic analysis

Question 1

What happens when covalent bonds absorb infrared energy?

Answer 1

Vibrate

Question 2

How do we interpret infrared spectra?

Answer 2

Match drop in % transmission with absorption data for different bonds

Question 3

What is the test for an alkene?

Answer 3

Add bromine water - orange to colourless if alkene present

Question 4

What is the test for a carboxylic acid?

Answer 4

Add a carbonate, test gas produced by bubbling through limewater - cloudy if CO₂ present

Question 5

What is the test for an alcohol?

Answer 5

Add acidified potassium dichromate, orange to green if primary or secondary alcohol

Question 6

Describe the Fehling’s test for aldehydes and ketones

Answer 6

Add compound being tested to Fehling’s solution in a water bath
Blue to red if positive (aldehyde)

Question 7

Describe how to use Tollen’s reagent to test for aldehydes and ketones

Answer 7

Add compound being tested to Tollen’s reagent in a water bath
Silver mirror precipitate if positive (aldehyde)