Organic analysis

Question 1

IDENTIFICATION OF FUNCTIONAL GROUS BY TEST TUBE REACTIONS
What reagent used to identify alkene and what are the observations?

Answer 1

Reagent: Bromine water
Observations: Orange —> colourless

Question 2

IDENTIFICATION OF FUNCTIONAL GROUS BY TEST TUBE REACTIONS
TEST 1 (fehling’s solution): What reagent used to identify aldehyde and what are the observations?

Answer 2

Reagent: Fehling’s solution
Observations: blue solution —> brick red precipitate

Question 3

IDENTIFICATION OF FUNCTIONAL GROUS BY TEST TUBE REACTIONS
TEST 2 (tollens’ reagent): What reagent used to identify aldehyde and what are the observations?

Answer 3

Reagent: Tollens’ reagent
Observations: produce silver mirror

Question 4

IDENTIFICATION OF FUNCTIONAL GROUS BY TEST TUBE REACTIONS
What reagent used to identify carboxylic acid and what are the observations?

Answer 4

Reagent: sodium carbonate
Observations: Effervescence of CO2

Question 5

IDENTIFICATION OF FUNCTIONAL GROUS BY TEST TUBE REACTIONS
What reagent used to identify primary and secondary alcohols and what are the observations?

Answer 5

Reagent: acidified potassium dichromate (K2CR2O7)
Observations: orange —> green

Question 6

IDENTIFICATION OF FUNCTIONAL GROUS BY TEST TUBE REACTIONS
What reagent used to identify halogenoalkane and what are the observations?

Answer 6

Reagent: Warm sodium hydroxide + acidify with nitric acid and silver nitrate
Observations: White precipitate of AgCl

Question 7

Can you state the mechanism of greenhouse effect ( 5 steps)?

Answer 7

1. UV wavelength radiation passes through atmosphere to the earth’s surface
2. Heats up the earth’s surface
3. Earth’s surface reflects infrared radiation
4. C=O bond in CO2 absorbs infrared radiation and re-emits it back to earth.
5. This energy is transferred to other molecules in the atmosphere by collisions, warming up the atmosphere

Question 8

What is the fingerprint region?

Answer 8

Part of the spectrum below 1500 cm-1 that is unique for every compound

Question 9

What are examples of spectroscopic techniques?

Answer 9

• infrared spectroscopy
• mass spectroscopy

Question 10

Why do bonds like C=O can absorb infrared radiation

Answer 10

Bonds like C=O bond can vibrate in the presence of infrared

Question 11

What does fingerprinting allow?

Answer 11

Allows identification of other molecules by comparison of spectra