Organic Observations and Deductions

Question 1

(1) Appearance and smell

a) Colourless liquid, characteristic spirit/alcohol smell
b) Colourless liquid, sharp and irritating smell
c) Fruity, sweet, or solvent-like smell

Answer 1

a) Alcohol
b) Carboxylic acid
c) Ester

Question 2

(2) Miscibility/Solubility in water

a) Mixes with water, forms one layer
b) Does not mix with water, forms two layers

Answer 2

a) Polar, can form hydrogen bonds with water, possibly an alcohol or carboxylic acid
b) Non-polar, cannot form hydrogen bonds with water

Question 3

(3) Combustion

a) Clean blue flame
b) Sooty orange flame

Answer 3

a) Low carbon content, possibly an alcohol

b) High carbon content, possibly an alkane or aliens

Question 4

(4) Bromine water

a) Bromine water changes colour from yellow/orange/brown to colourless
b) Yellow/orange/brown colour of bromine water remains

Answer 4

a) C=C present, alkene

b) No C=C present

Question 5

(5) Silver nitrate solution with ethanol

a) White ppt, forms slowly
b) Cream ppt, forms more quickly
c) Yellow ppt, forms reasonably quickly

Answer 5

a) Chloroalkane
b) Bromoalkane
c) Iodoalkane

Question 6

(6) Phosphorus pentachloride

a) Gas released; misty fumes; solid disappears; heat released; white smoke with concentrated ammonia solution
b) No gas released; no white smoke with concentrated ammonia solution

Answer 6

a) Alcohol, or -OH group, present; HCl gas released; white smoke is ammonium chloride
b) Not an alcohol, no -OH group present

Question 7

(7) Acidified potassium dichromate

a) Orange solution changes to green
b) Solution remains orange

Answer 7

a) Primary or secondary alcohol

b) Not primary or secondary alcohol

Question 8

(8) Iodoform

a) Yellow ppt
b) No yellow ppt

Answer 8

a) Secondary alcohol

b) Not secondary alcohol

Question 9

(9) Sodium carbonate/hydrogencarbonate

a) Gas released; solid disappears; limewater changes from colourless to milky
b) No gas released

Answer 9

a) Carboxylic acid (COOH group present); carbon dioxide gas released
b) Not carboxylic acid (no COOH group)

Question 10

(10) Magnesium

a) Gas released; magnesium disappears; gas produces squeaky pop with lit splint
b) No gas released

Answer 10

a) Carboxylic acid (COOH group present); hydrogen gas released
b) Not carboxylic acid (no COOH group)