Chapter 27 - The Atmosphere Flashcards
What is the percentage of different gases in the air
Nitrogen - 78%
Oxygen - 21%
Argon, carbon dioxide, water vapour - 1%
Give four uses for CO2
- Refrigeration
- Stage effects
- Fizzy drinks
- Fire extinguishers
How can oxygen gas be prepared?
Oxygen gas can be prepared by reacting hydrogen peroxide with manganese dioxide
How can carbon dioxide be prepared?
Carbon dioxide can be prepared by reacting dilute hydrochloric acid with calcium carbonate
What is the chemical equation for the preparation of oxygen gas?
hydrogen peroxide + manganese dioxide —> oxygen + water
H2O2 + MnO2 —> O2 + H2O
What is the chemical equation for the preparation of carbon dioxide gas?
hydrochloric acid + calcium carbonate —> calcium chloride + water + carbon dioxide
2HCl + CaCO3 —> CaCl2 + H2O + CO2
What happens when you place a glowing splint in a jar of oxygen?
It relights
What would happen if a burning piece of carbon was placed in a jar of oxygen and a piece of moist litmus paper was later added?
The carbon burns brightly in the oxygen and carbon dioxide gas is produced. The litmus paper turns red showing an acid has been formed
What would happen if a burning piece of Magnesium ribbon was placed in a jar of oxygen and moist litmus paper was later added?
The magnesium burns brightly in the oxygen and a white powder called magnesium oxide is formed. The litmus paper turns blue showing this is a base
What would happen if you put a piece of moist litmus paper into a jar of carbon dioxide?
The litmus paper turns red, showing carbon dioxide is an acidic gas
What would happen if you put a small amount of limewater into a jar of carbon dioxide and shook it?
The limewater would turn milky in colour
What would happen if you placed a lit candle in an empty beaker and inverted a jar of carbon dioxide above it? What does the outcome show?
The candle is extinguished by the carbon dioxide. This shows:
- CO2 is more dense than air
- It puts out fire
What is the word and chemical equation of the reaction of carbon dioxide with limewater?
Calcium hydroxide + carbon dioxide –> calcium carbonate + water
Ca(OH)2 + CO2 –> CaCO3 + H2O
