Identifying Molecules

Question 1

Ammonia (NH3)

A colourless alkaline gas with a pungent smell

Answer 1

Carefully smell the gas, and hold damp litmus paper in it

Recognisable odour and red litmus turns blue

Question 2

Carbon dioxide

A colourless, weakly acidic gas.

Answer 2

Bubble gas through limewater

Limewater turns cloudy or milky

Question 3

Chlorine Cl2

A green poisonous gas which bleaches dyes

Answer 3

Hold damp litmus in the gas, in a fume cupboard

Litmus paper turns white

Question 4

Hydrogen

A colourless gas

Answer 4

Collect the gas in an upside down test tube and hold a lit splint to the mouth of the test tube
The gas burns with a squeaky “pop” sound

Question 5

Oxygen

A colourless gas which supports combustion

Answer 5

Collect the gas in an upside down test tube. Place an extinguished splint into the test tube
The splint re-ignites

Question 6

H20

Answer 6

Add anhydrous copper sulfate, if white turns blue water is present.
Or Anhydrous Cobalt chloride blue turns pink

Question 7

Sulfur Dioxide

Answer 7

Turns acidified ( needs H+ ion in redox) aqueous potassium manganese from Purple to colourless.

Question 8

Nitrogen Oxide

Answer 8

Choking smell and brown colour

Turns moist indicator pink