Gas Tests and Reactions

This lesson covers methods to test for the presence of hydrogen, oxygen, carbon dioxide, ammonia, and chlorine gases in the laboratory. Each gas has distinct testing methods: hydrogen produces a squeaky pop with a lit splint, oxygen relights a glowing splint, carbon dioxide turns lime water milky, ammonia turns damp red litmus paper blue and forms ammonium chloride smoke, and chlorine turns damp blue litmus paper red and bleaches it. The lesson emphasizes the importance of these tests due to the colorless and odorless nature of many gases.

Why is it difficult to identify gases based on their appearance?

• Gases are always visible.

• Gases are often colorful and fragrant.

• Gases are usually colorless and odorless.

• Gases have a distinct taste.

What sound indicates the presence of hydrogen when tested with a lit splint?

• No sound

• A squeaky pop

• A soft hiss

• A loud bang

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

• It extinguishes

• It relights

• It changes color

• It remains unchanged

Why does hydrogen produce a pop sound when ignited?

• It is due to the gas being colorless.

• It is a reaction with nitrogen.

• It is a result of a mini explosion.

• It is because hydrogen is non-flammable.

What is the concentration of oxygen in air compared to the reaction vessel?

• 10% in air

• 5% in air

• 21% in air

• 50% in air

What happens when carbon dioxide is bubbled through lime water?

• The lime water turns red.

• The lime water turns blue.

• The lime water turns milky.

• The lime water turns clear.

What color change occurs to damp red litmus paper in the presence of ammonia?

• It turns blue.

• It remains red.

• It turns green.

• It turns yellow.

What is formed when ammonia reacts with concentrated hydrochloric acid?

• Ammonium phosphate

• Ammonium chloride

• Ammonium nitrate

• Ammonium sulfate

What happens to damp blue litmus paper in the presence of chlorine?

• It turns green.

• It turns red and then bleaches to white.

• It turns yellow.

• It remains blue.

Which gas test involves observing a color change in litmus paper?

• Ammonia

• Carbon dioxide

• Oxygen

• Hydrogen