Tests for Gases

• This video is about how to test for four carbon gases: chlorine, oxygen, hydrogen, and carbon dioxide
• Steps to test for chlorine gas

  1️⃣ Fill a test tube with the gas sample

  2️⃣ Dampen a piece of blue litmus paper

  3️⃣ Insert the damp litmus paper into the test tube

  4️⃣ Observe if the paper turns white
• Chlorine gas turns blue litmus paper red before it turns white due to the formation of hydrochloric acid.
• Why does blue litmus paper turn red when exposed to chlorine gas?

  Forms hydrochloric acid
• Chlorine gas is poisonous, so it is important to use a fume cupboard
• Steps to test for oxygen gas

  1️⃣ Use a glowing splint without a flame

  2️⃣ Insert the glowing splint into the gas sample

  3️⃣ Observe if the splint relights
• What happens to a glowing splint when inserted into oxygen gas?

  It relights
• Burning requires oxygen, so a glowing splint relights in the presence of oxygen because it supplies additional oxygen
• Steps to test for hydrogen gas

  1️⃣ Fill a test tube with the gas sample

  2️⃣ Use a lit splint

  3️⃣ Move the burning splint close to the test tube

  4️⃣ Observe if a squeaky pop occurs
• What sound is produced when hydrogen gas reacts with a lit splint?

  Squeaky pop
• Calcium hydroxide is also known as lime water
• Steps to test for carbon dioxide gas

  1️⃣ Fill a test tube with the gas sample

  2️⃣ Bubble the gas through lime water

  3️⃣ Observe if the lime water turns cloudy
• What happens to lime water when carbon dioxide gas is bubbled through it?

  It turns cloudy
• Carbon dioxide reacts with calcium hydroxide to form calcium carbonate and water, which causes the solution to turn cloudy.