Tests For Gases (AQA GCSE Combined Science: Synergy: Physical Sciences): Revision Note

Test for hydrogen gas

What is the "squeaky pop" test?

• The test for hydrogen gas consists of holding a burning splint held at the open end of a test tube of gas

• If the gas is hydrogen it burns with a loud “squeaky pop” which is the result of the rapid combustion of hydrogen with oxygen to produce water

• Be sure not to insert the splint right into the tube, just at the mouth, as the gas needs air to burn

Test for hydrogen gas

A burning splint gives a 'squeaky pop' sound 

Test for oxygen gas

• The test for oxygen consists of placing a glowing splint inside a test tube of gas

• If the gas is oxygen the splint will relight

Test for oxygen 

Oxygen relights a glowing splint

Test for chlorine gas

• The test for chlorine gas makes use of litmus paper

• If chlorine gas is present, damp blue litmus paper will turn red and then be bleached white

• It turns red initially as acids are produced when chlorine comes into contact with water

• Chlorine also has a characteristic sharp, choking smell 

• Chlorine should always be handled in a fume cupboard due to its toxicity

Test for chlorine gas

Chlorine bleaches damp blue litmus paper white