The Air And Oxygen Flashcards
Gas percentages in the air
Nitrogen : 78%
Oxygen : 21%
Other : 1%
Word equation to make oxygen
Hydrogen peroxide - manganese dioxide - water + oxygen
Chemical equation to make oxygen
2H2O2 - MnO2 - 2H2O + O2
Word equation for carbon dioxide
Calcium carbonate + Hydrochloric acid — calcium chloride + water + carbon dioxide
Chemical equation for carbon dioxide
CaCO3 + 2HCl — CaCl2 + H2O + CO2
Catalyst
A catalyst is a substance that changes the speed of a chemical reaction without being used up in the reaction
Properties of oxygen
Physical :
Colourless, odourless, tasteless gas
Slightly soluble in water
Slightly heavier than air
Chemical :
Supports combustion
Reacts with most substances to form oxides
No effect on litmus
Uses of oxygen : breathing
Used in hospitals for people who have difficulty breathing
Used to revive people who have been in smoke filled rooms or drowning
Mountain climbers and underwater work uses cylinders of oxygen
Uses of oxygen : burning and welding
Acetylene burns fiercely in oxygen to produce a 3000 *C flame which can cut metals or join them together
Uses of oxygen : space rockets
Rockets carry their own oxygen and hydrogen.
Limewater equation
Limewater (calcium hydroxide) + carbon dioxide = chalk + water
Limewater chemical equation
Ca(OH)2 + CO2 = CaCO3 + H2O
Properties of carbon dioxide
Physical :
Colourless, odourless, tasteless gas
Slightly soluble in water
More dense than air
Chemical :
Does not support combustion
Turns limewater milky
Dissolves in water to form carbonic acid
Uses of carbon dioxide
Fizzy drinks - carbon dioxide under pressure
Fire extinguishers - flows on top of fire and extinguishes it
Refrigeration - carbon dioxide under pressure is dry ice
Special effects on stage - dry ice in warm water makes carbon dioxide gas mist
