Identification of functional groups

Question 1

What groups are soluble in water/ have one layer?

Answer 1

Small carbon chains (1-5), alcohols, amides, aldehydes & ketones, carboxylic acids and small esters

Question 2

What groups are insoluble in water/ make 2 layers?

Answer 2

Large alcohols, amines, carboxylic acids, amides and esters and ALL alkanes, alkynes and haloalkanes

Question 3

What turns moist red litmus paper blue?

Answer 3

Amines

Question 4

What turn moist blue litmus paper reds?

Answer 4

Carboxylic acids

Question 5

What turns UI solution from green to blue

Answer 5

Amines

Question 6

What turns UI solution from green to orange

Answer 6

Carboxylic acid

Question 7

What turns Cr2O7^2-/H+ (aq) to Cr^3+ (aq) changing orange to green when heated

Answer 7

Primary alcohols, secondary alcohols and aldehydes

Question 8

What turns Mno4-/H+ (aq) to Mn^2+ (aq), changing purple to colourless

Answer 8

Primary alcohols, secondary alcohols and aldehydes

Question 9

What turns Mno4-/H+ (aq) to Mn^2+ (aq), changing purple to colourless

Answer 9

Alkenes

Question 10

What turns Mno4-/H+ (aq) to MnO2 , changing purple to brown precipitate

Answer 10

Alkenes

Question 11

Reacts with NAHCO3 or NA2CO3 solid or solution to produce colourless gas CO2

Answer 11

Carboxylic acid

Question 12

Reacts with Mg (or other reactive metals) to produce colourless gas H2

Answer 12

Carboxylic acid

Question 13

Has a fishy smell

Answer 13

Amines

Question 14

Have a ‘sharp’ or vinegary smell

Answer 14

Carboxylic acids

Question 15

Rapidly decolourise orange bromine water, Br2

Answer 15

Alkenes and alkynes (unsaturated)

Question 16

Slowly decolourise orange bromine water, Br2 needing UV light and heat

Answer 16

Alkanes/other molecules with C-C bonds (saturated)

Question 17

Usually have a pleasant fruity smell

Answer 17

Esters

Question 18

React vigorously with water, and make HCl fumes

Answer 18

Acyl chloride

Question 19

React with blue Cu^2+ (aq) to form deep blue solution

Answer 19

Amines

Question 20

Give a silver mirror (black ppt) with Tollens’s reagent

Answer 20

Aldehydes

Question 21

Give a red/ orange precipitate of Cu2O with Benedict’s or Fehling’s reagent (Cu^2+)

Answer 21

Aldehydes

Question 22

Able to rotate plane polarised light

Answer 22

Molecules with asymmetrical C atom

Question 23

Soluble in water- one layer

Answer 23

Polar molecule

Question 24

Insoluble in water- two layers

Answer 24

Non-polar molecule

Question 25

Release NH3 gas if heated with NaOH, turns red litmus blue

Answer 25

Amides