Organic Analysis ORGANIC

Question 1

What test tube reaction is used for alkenes?

Answer 1

Shake with bromine water

Question 2

What result will alkenes give in test tube reaction?

Answer 2

Orange to colourless

Question 3

What test tube reaction is used for alkenes?

Answer 3

Add aqueous sodium hydroxide and warm gently
Acidify with nitric acid
Add silver nitrate

Question 4

What result will halogenoalkanes give in test tube reaction?

Answer 4

Coloured precipitate of AgX forms

Question 5

What colour precipitate is AgCl?

Answer 5

White

Question 6

What colour precipitate is AgBr?

Answer 6

Cream

Question 7

What colour precipitate is AgI?

Answer 7

Yellow

Question 8

What test tube reaction is used for alcohols?

Answer 8

Add acidified potassium dichromate solution

Question 9

What result will alcohols give in test tube reaction?

Answer 9

Varies depending on alcohol type

Question 10

What result will primary alcohol give in test tube reaction?

Answer 10

Orange turns to green

Question 11

What result will secondary alcohols give in test tube reaction?

Answer 11

Orange turns to green

Question 12

What result will tertiary alcohol give in test tube reaction?

Answer 12

No reaction or colour change

Question 13

What test tube reaction is used for aldehydes?

Answer 13

Warm with Tollen’s reagent
OR
Warm with Fehling’s reagent

Question 14

What result will aldehyde give in Tollen’s reagent?

Answer 14

Silver mirror forms

Question 15

What result will aldehyde give in Fehling’s reagent?

Answer 15

Blue solution turns to red precipitate

Question 16

What test tube reaction is used for carboxylic acids?

Answer 16

Add sodium hydrogen carbonate

Question 17

What result will carboxylic acid give in test tube reaction?

Answer 17

CO₂ gas formed

Question 18

What is mass spectroscopy?

Answer 18

Analytical technique used to identify unknown compounds

Question 19

Describe process of mass spectroscopy.

Answer 19

Molecules in sample bombarded with high energy electrons which cause molecules to lose electron
Molecular ion can further fragment to new ions, molecules and radicals
Fragmented ions are accelerated by electric field and separated by deflecting into detector

Question 20

What are fragmented ions separated on in mass spectrometry?

Answer 20

Mass to charge ratio

Question 21

Which ions are detected first in mass spectroscopy?

Answer 21

Smaller and more positively charged

Question 22

What does the base peak in mass spectroscopy correspond to?

Answer 22

The most abundant ion

Question 23

What are isotopes?

Answer 23

Atoms of the same element that contain the same number of protons and electrons but a different number of neutrons

Question 24

What is mass spectroscopy used to find?

Answer 24

Relative abundance of isotopes experimentally

Question 25

What is meant by the relative abundance of an isotope?

Answer 25

Proportion of one particular isotope in a mixture of isotopes found in nature

Question 26

What does the height of peaks in mass spectroscopy show?

Answer 26

Proportion of each isotope present

Question 27

What do peaks in mass spectrum correspond to?

Answer 27

Certain fragment with particular m/z value

Question 28

What is the peak with the highest m/z value in mass spectrum?

Answer 28

The molecular ion peak

Question 29

What is molecular ion peak used for?

Answer 29

Identify molecular mass of compound

Question 30

What is used to further determine structure of unknown compound after M+ peak?

Answer 30

Fragmentation

Question 31

How are simple alkanes fragmented in mass spectroscopy?

Answer 31

Breaking C-C bonds

Question 32

Why do halogenoalkanes often have multiple peaks around molecular ion peak?

Answer 32

Different isotopes of halogens

Question 33

What is infrared spectroscopy?

Answer 33

A technique used to identify compounds based on changes in vibrations of atoms when they absorb IR of certain frequencies

Question 34

What is a spectrophotometer?

Answer 34

Irradiates sample with electromagnetic waves in infrared region and deitects intensity of wavelength of IR radiation through sample

Question 35

What is meant by resonance frequency?

Answer 35

Specific frequency at which molecules will vibrate to stimulate larger vibrations