Science - Chapter 10: Gases

What are the gases found in air?

• Nitrogen

• Oxygen

• Carbon Dioxide

• Noble Gas

• Water Vapour

What is the percentage of nitrogen in air?

79%

What is the percentage of oxygen in air?

21%

What is the percentage of carbon dioxide in air?

0.03%

What is the percentage of noble gas in air?

~1%

What is the percentage of water vapour in air?

Varies

Why does the percentage of water vapour in air vary?

In humid countries, there is high percentage of water vapor in the air.

What is the word equation of photosynthesis?

Carbon Dioxide + Water =(Light +Chlorophyll) Glucose + Oxygen

What is the word equation of respiration?

Glucose + Oxygen = Carbon Dioxide + Water

What are the properties of oxygen?

• It’s odorless

• It’s colorless

• It supports life

• It supports combustion

What is the identification of oxygen?

Test: Use glowing splint

Result: Glowing splint will rekindle

What are the uses of oxygen?

• Support combustion

• Scuba divers carry a tank that stores oxygen.

What are the 2 factors which cause iron to rust?

• Oxygen

• Water

What are the properties of carbon dioxide?

• It is odorless

• It is colorless

• It does not support combustion

What is the identification of carbon dioxide?

Test: Use limewater

Result: Limewater turns milky

What are the uses of carbon dioxide?

• It is used as a fire extinguisher

• Dry ice is used to freeze and preserve food like ice cream

What is the abundant gas in the air?

Nitrogen

Why is there no test for the presence of nitrogen?

It is an unreactive gas.

What are the properties of nitrogen?

• It is odorless

• It is colorless

• It doesn’t support combustion

What are the uses of nitrogen?

• Making fertilisers

• Used as preservative in the food industry

What is another term for noble gases?

Inert gases

What are examples of noble gases?

• Argon

• Krypton

• Xenon

• Radon

What are properties of noble gases?

• It is unreactive

• It is colorless

• It doesn’t support combustion

What are uses of helium?

• Used in airships

• Used in balloons

What are uses of neon?

Used in advertising signs because neon is able to produce bright and colorful light. 

What are the uses of argon?

To fill in the light bulb because argon prevents the filament from burning

What are the properties of water vapour?

• It is odorless

• It is colorless

What is the identification of water vapour?

Test: Use blue cobalt chloride paper

Result: Turns pink

What is the first element of the periodic table?

Hydrogen

What is the lightest of all gases?

Hydrogen

What are the properties of hydrogen?

• Odorless

• Colorless

• Highly flammable

• Burns in air to produce water vapour

What is the identification of hydrogen?

Test: Use a lighted splint

Result: Splint will extinguish with a ‘pop’ sound

What is the preparation of hydrogen gas?

Metal + acid = salt + hydrogen gas