Chemical Tests

Question 1

Name the reagents that a student could use to identify a sample that’s an aldehyde

Answer 1

Fehling’s solution - blue to red-orange precipitate
Tollen’s reagent - silver mirror

Question 2

Reagent to identify carboxylic acid

Answer 2

NaHCO3 (metal carbonate) - fizz/effervescence

Because they are acids, they will react with metal carbonates to give salt and water and carbon dioxide

Question 3

Oxidation of Alcohols

Answer 3

Add acidified potassium dichromate K2Cr2O7

Tertiary alcohol doesn’t “OXIDISE”(OXIDISE keyword)

Secondary alcohols always make KETONES(orange to green)

Primary alcohols REFLUXED make CARBOXYLIC ACIDS, when DISTILLED make ALDEHYDES

Question 4

Conditions for Elimination Mechanism

Answer 4

Hot temperature
Ethanolic/Alcoholic Solvent
Type of halogenoalkane(secondary/Tertiary)

Question 5

Conditions For Nucleophilic Substitution Mechanism

Answer 5

Warm Temperature
Aqueous solvent
Type of halogenoalkane (primary/secondary)

Question 6

Chemical Test For Alkenes

Answer 6

Add BROMINE WATER, it turns from orange to COLOURLESS