QA Test for Gases

Question 1

Method for H2

Answer 1

Place lighted splint beside mouth of test tube

Question 2

Observation for H2

Answer 2

Lighted splint extinguishes with a ‘pop’ sound

Question 3

Method for CO2

Answer 3

Bubble gas through limewater

Question 4

Observation for CO2

Answer 4

Forms white precipitate in limewater (CaCO3)

Question 5

Method for O2

Answer 5

Insert glowing splint into test tube

Question 6

Observation for O2

Answer 6

Glowing splint rekindles/relights

Question 7

Methods for H2O

Answer 7

Place cobalt chloride paper at mouth of test tube
OR
Pass gas over anhydrous copper (II) sulfate crystals

Question 8

Observations for H2O

Answer 8

Cobalt chloride paper turns from blue to pink
OR
Anhydrous copper (II) sulfate crystals turn from white to blue

Question 9

Method for Cl2

Answer 9

Place moist blue litmus paper at mouth of test tube

Question 10

Observation for Cl2

Answer 10

Moist blue litmus paper turns red then bleaches

Question 11

Methods for SO2

Answer 11

Place filter paper soaked with acidified potassium dichromate (VI) at mouth of test tube
OR
Place filter paper soaked with acidified potassium manganate (VII) at mouth of test tube

Question 12

Observations for SO2

Answer 12

Potassium dichromate (VI) turns from orange to green
OR
Potassium manganate (VII) turns from purple to colourless

Question 13

Method for NH3

Answer 13

Place moist red litmus paper at mouth of test tube

Question 14

Observation for NH3

Answer 14

Moist red litmus paper turns blue