2c Gases in the atmosphere

Question 1

What is the percentage of nitrogen (N2) in the air?

Answer 1

78%

Question 2

What is the percentage of oxygen (O2) in the air?

Answer 2

21%

Question 3

What is the percentage of argon in the air?

Answer 3

0.94%

Question 4

What is the percentage of Carbon Dioxide in the air?

Answer 4

0.04%

Question 5

What are the properties of nitrogen?

Answer 5

• Nitrogen gas is difficult to notice – it’s colourless, odourless and insoluble in water.
• Its structure is two nitrogen atoms joined by a triple covalent bond. This means it is diatomic.
• The triple covalent bond is very strong, and a great deal of energy is required to break it.
• The bond needs to be broken before nitrogen will react with other atoms.

Question 6

What are the uses of nitrogen?

Answer 6

• Used to make fertilisers, nitric acid, nylon dyes and explosives
• Nitrogen must first react with hydrogen to produce NH3 - this is called the harbor process
• It can also be used for filling light bulbs
• Liquid nitrogen is very cold and can be used as a coolant
• Nitrogen gas provides an
  inert atmosphere in food packaging, helping to keep the contents fresh.

Question 7

What are the properties of Oxygen?

Question 8

What are the uses of Oxygen?

Question 9

What are the properties of Argon?

Question 10

What are the uses of Argon?

Question 11

What are the properties of Carbon Dioxide?

Question 12

What are the uses of Carbon Dioxide?

Question 13

What is the method for the heating copper turnings experiment to figure out how much % of oxygen is in the air?

Answer 13

• Fill a gas syringe with 100cm3 of air.
• Start to heat the copper turnings and then gently pass the air from one syringe to the other.
• Continue to pass the air backwards and forwards until the volume of the gas syringe remains fixed

Volume of air in syringe at start - 100cm3
Volume of air in syringe at end - 79cm3
Volume of air used up - 21cm3
Volume of oxygen used up - 21%

Question 14

What is the method of how to determine the % of oxygen used up during rusting?

Question 15

What is the method for burning phosphorus in air to determine the % of oxygen?

Answer 15

• Light the phosphorus with a hot wire
• It reacts with the oxygen in the air and causes the water level in the bell jar to rise by about 20%
• Place the phosphorus in the evaporating dish and float it in the bell jar
• Light the phosphorus
• Quickly cover the dish with a bell jar in the trough
• Note the water level in the bell jar
• Leave the apparatus until the phosphorus is extinguished
• Measure the final water level in the bell jar, the decrease in the volume of air is the volume of air originally in the jar
• Calculate the % of oxygen in air using the change in water level / original volume of air in the bell jar x 100