GCSE Chemistry - How to Test for Gases - Testing for Chlorine / Oxygen / Hydrogen / CO2 #64

This video tutorial explains how to test for four gases: chlorine, oxygen, hydrogen, and carbon dioxide. The chlorine test involves using damp blue litmus paper, which turns white if chlorine is present. The oxygen test uses a glowing splint that relights in the presence of oxygen. For hydrogen, a burning splint produces a squeaky pop sound. The carbon dioxide test involves bubbling the gas through lime water, which turns cloudy if carbon dioxide is present. Safety precautions, such as wearing a mask when testing chlorine, are also discussed.

What color change occurs on damp blue litmus paper when chlorine is present?

• Blue to white

• Blue to red

• Red to blue

• White to blue

Why might the litmus paper briefly turn red before turning white in the presence of chlorine?

• Because of the presence of oxygen

• Due to the presence of carbon dioxide

• Because chlorine forms hydrochloric acid

• Due to the formation of sulfuric acid

What happens to a glowing splint in the presence of oxygen?

• It makes a popping sound

• It extinguishes

• It turns blue

• It relights

What sound is heard when hydrogen gas is tested with a burning splint?

• A hissing sound

• No sound

• A squeaky pop

• A loud bang

What change occurs in lime water when carbon dioxide is bubbled through it?

• It turns blue

• It becomes clear

• It turns cloudy

• It remains unchanged