8.2 Identification of common gases

• What is the chemical formula for oxygen gas?

  O₂
• What color is chlorine gas?

  Greenish-yellow
• Sulfur dioxide is acidic and turns blue litmus paper red
• Steps in the chemical test for hydrogen gas:

  1️⃣ Bring a glowing wooden splint near the gas

  2️⃣ The splint makes a "pop" sound

  3️⃣ Hydrogen ignites
• What color does damp blue litmus paper turn when exposed to chlorine gas?

  Red
• Sulfur dioxide turns blue litmus paper red
• When recording observations, you should include the date, time, and conditions
• Steps for analyzing sample results effectively

  1️⃣ Observe changes

  2️⃣ Record observations

  3️⃣ Interpret results

  4️⃣ Compare with standards
• Oxygen supports combustion and is colorless and odorless.

  True
• What is the chemical formula for hydrogen gas?

  H₂
• Oxygen gas supports combustion.


  True
• Ammonia gas is alkaline.


  True
• Hydrogen gas is flammable.


  True
• What happens when a glowing wooden splint is brought near oxygen gas?

  Relights and burns brightly
• Ammonia turns damp red litmus paper blue.


  True
• What is the first step in analyzing sample results using chemical observations?

  Observe
• Steps to analyze sample results using chemical observations:

  1️⃣ Observe any changes or reactions

  2️⃣ Record observations accurately

  3️⃣ Interpret results using chemical tests
• Interpreting results requires prior knowledge of chemical tests and observations.

  True
• Match the gas with its property:

  Hydrogen ↔️ Flammable

  Oxygen ↔️ Supports combustion

  Carbon dioxide ↔️ Does not support combustion

  Chlorine ↔️ Greenish-yellow, toxic

  Ammonia ↔️ Pungent odor, alkaline

  Sulfur dioxide ↔️ Pungent odor, acidic
• Which gas does not support combustion and is colorless and odorless?

  Carbon dioxide
• Sulfur dioxide is a colorless gas with a pungent odor and is acidic
• What happens when a glowing wooden splint is brought near oxygen gas?

  The splint relights
• Red litmus paper turns blue in the presence of ammonia gas.

  True
• Blue litmus paper turning red indicates the presence of an acidic gas like chlorine or sulfur dioxide.


  True
• Hydrogen gas is colorless and odorless.

  True
• Carbon dioxide is a colorless and odorless gas that does not support combustion
• What type of odor does sulfur dioxide have?

  Pungent
• Match each gas with its physical property:

  Oxygen ↔️ Supports combustion

  Carbon dioxide ↔️ Does not support combustion

  Chlorine ↔️ Pungent odor, toxic

  Ammonia ↔️ Pungent odor, alkaline

  Sulfur dioxide ↔️ Pungent odor, acidic
• Carbon dioxide turns limewater milky
• Interpreting chemical observations requires prior knowledge of chemical tests.


  True
• What should you note when observing a chemical reaction?

  Color, odor, texture, gas evolution, temperature changes
• What should you compare your results with to identify patterns?

  Known standards or previous samples
• Hydrogen is a colorless, odorless, and flammable
• What is the color and property of chlorine gas?

  Greenish-yellow, toxic
• Match the gas with its physical property:

  Hydrogen ↔️ Flammable

  Oxygen ↔️ Supports combustion

  Carbon dioxide ↔️ Does not support combustion

  Chlorine ↔️ Greenish-yellow, toxic

  Ammonia ↔️ Pungent odor, alkaline

  Sulfur dioxide ↔️ Pungent odor, acidic
• Carbon dioxide turns limewater milky.


  True
• Sulfur dioxide forms an acidic solution in water, which turns blue litmus paper red
• What does a relighting glowing splint indicate?

  Presence of oxygen
• Ammonia gas is colorless, has a pungent odor, and is alkaline.


  True
• Steps in the chemical test for identifying hydrogen gas

  1️⃣ Hold a lit wooden splint near the gas

  2️⃣ If hydrogen is present, it will make a pop sound