Gas Chemistry

Question 1

Uses of Carbon Dioxide

Answer 1

• In fire extinguishers
• In fizzy drinks

Question 2

Gas Collection

Answer 2

• Upward delivery for gases less dense than air
• Downward displacement for gases denser than air

Question 3

Test for Carbon Dioxide

Answer 3

• Bubble gas through limewater - turns milky
• If excess COz is added, the milky precipitate dissolves

Question 4

Chemical Properties of Carbon Dioxide

Answer 4

• Reacts with water to form weak carbonic acid
• Reacts with alkalis to form a salt and water

Question 5

Carbon Dioxide

Answer 5

• Colourless, odourless gas
• Low solubility in water
• More dense than air

Question 6

Preparation of Carbon Dioxide

Answer 6

Reaction of calcium carbonate with dilute hydrochloric acid

Question 7

Chemical Properties of Oxygen

Answer 7

• Supports combustion
• Reacts with metals to form solid basic oxides
• Reacts with non-metals to form gaseous acidic oxides

Question 8

Test for Oxygen

Answer 8

Apply a glowing splint - it relights

Question 9

Uses of Oxygen

Answer 9

• In medicine
• In welding

Question 10

Oxygen

Answer 10

• Colourless, odourless gas
• Slightly soluble in water
• Slightly more dense than air

Question 11

Preparation of Oxygen

Answer 11

Decomposition of hydrogen peroxide using manganese(IV) oxide catalyst

Question 12

Uses of Manganese(IV) oxide

Answer 12

Manganese(IV) oxide is used as a catalyst to speed up the
decomposition of hydrogen peroxide

Question 13

Hydrogen as a clean fuel

Answer 13

• Produces only water when burned
• But manufacturing hydrogen may use electricity from fossil fuels

Question 14

Dangers of hydrogen

Answer 14

Hydrogen is extremely flammable so : leaks could lead to an explosion, requiring high level safety controls

Question 15

Preparation of Hydrogen

Answer 15

Reaction of dilute hydrochloric acid with a metal

Question 16

Physical Properties of Hydrogen

Answer 16

• Colourless, odourless gas
• Insoluble in water
• Less dense than air

Question 17

Uses of Hydrogen

Answer 17

• Meteorological balloons
• Hardening oils to make solid fats
• Potential as a clean fuel

Question 18

Uses of Ammonia

Answer 18

• Reacts with acids to produce ammonium salts used as artificial
fertilisers

Question 19

Hydrogen

Answer 19

• First element in the Periodic Table
• Exists as a diatomic molecule
• Occurs in water, oil, natural gas and all living things

Question 20

Test for Ammonia

Answer 20

• Dip glass rod in concentrated hydrochloric acid and hold close to the gas
• White smoke of ammonium chloride is formed if ammonia is
present

Question 21

Uses of Nitrogen

Answer 21

• Liquid nitrogen used as a coolant
• Inert atmosphere in food packaging

Question 22

Ammonia (NH3)

Answer 22

• Colourless gas with pungent smell
• Very soluble in water forming an alkaline solution

Question 23

Physical Properties of Nitrogen

Answer 23

• Colourless, odourless gas
• Insoluble in water
• Extremely unreactive
• Exists as a diatomic molecule

Question 24

Why is nitrogen unreactive?

Answer 24

Nitrogen is unreactive due to the strong triple covalent bond between the two nitrogen atoms which requires substantial energy to break before the nitrogen atoms can react

Question 25

Composition of Air

Answer 25

• Nitrogen
• Water vapour
• Oxygen
• Noble gases & Argon
• CO2

Question 26

Nitrogen

Answer 26

• Most abundant constituent of the atmosphere
• Present in all living matter
• Essential part of all plant and animal life

Question 27

Air

Answer 27

Mixture of gases that makes up the Earth’s atmosphere and is essential for life