O1: 16 Organic Analysis

Question 1

What’s the test for primary/secondary/tertiary alcohols?

Answer 1

1. Add acidified potassium dichromate.
2. Warm the mixture gently.
3. Primary and secondary - orange to green
   Tertiary - no visible change

Question 2

What are the tests to distinguish between aldehydes and ketones?

Answer 2

1. Warm with Fehling’s solution.
   Aldehyde - blue to red precipitate
   Ketone - no visible change
2. Warm with Tollen’s reagent.
   Aldehyde - silver mirror forms
   Ketone - no visible change

Question 3

What’s the test for alkenes?

Answer 3

1. Add bromine water and shake.
2. Alkene - orange to colourless
   Not alkene - no visible change.

Question 4

What’s the test for carboxylic acids?

Answer 4

1. Add Na2CO3.
2. Bubble gas produced through limewater.
3. Carboxylic acid - effervescence as CO2 produced.
   Not acid - no visible change

Question 5

What can mass spectrometry be used for?

Answer 5

To determine the molecular formula of a compound.

Question 6

What do bonds do that allow infrared spectroscopy?

Answer 6

Bonds in a molecule absorb infrared radiation at characteristic wavenumbers.

Question 7

What does fingerprinting allow?

Answer 7

The identification of a molecule by comparison of spectra.

Question 8

How can you identify molecules using infrared spectra?

Answer 8

Compare the fingerprint region with known spectra and an exact match is the molecule.

Question 9

How is infrared radiation absorption linked to global warming?

Answer 9

Greenhouse effect - greenhouse gases absorb infrared radiation re-emit some back towards Earth.

Human activity has increased concentration of greenhouse gases so global warming is happening.