31.2- ORGANIC ANALYSIS

Question 1

What can a compound being solid suggest?

Answer 1

long carbon chain or ionic bonding

Question 2

What can a compound being liquid suggest?

Answer 2

suggests medium length carbon chain or polar or hydrogen bonding

Question 3

What can a compound being a gas suggest?

Answer 3

suggest short carbon chain, little or no polarity

Question 4

What does a compound dissolving in water suggest?

Answer 4

suggests polar groups

Question 5

What does a compound not dissolving in water suggest?

Answer 5

suggests no polar groups

Question 6

What does a compound burning with a smoky flame suggest?

Answer 6

suggests high C:H ratio, possibly aromatic

Question 7

What does a non-smoky flame suggest?

Answer 7

suggests low C:H ratio, probably non-aromatic

Question 8

What is the test for an alkene -C=C-?

Result?

Answer 8

shake with bromine water

red-brown colour disappears

Question 9

What is the test for a halogenoalkane R-X?

Result?

Answer 9

1. add NaOH(aq) and warm
2. acidify with HNO3
3. add AgNO3(aq)

precipitate of AgX

Question 10

What is the test for an alcohol R-OH?

Result?

Answer 10

add acidified K2Cr2O7

orange colour turns green with primary or secondary alcohols (also with aldehydes)

Question 11

What is the test for an aldehyde R-CHO?

Result?

Answer 11

warm with Fehling's solution 
or 
warm with Tollen's solution 
or 
add acidified K2Cr2O7

blue colour turns to red precipitate
silver mirror forms
orange colour turns green

Question 12

What is the test for a carboxylic acid R-COOH?

Answer 12

add NaHCO3(aq)

bubbles observed as carbon dioxide given off