air by mr. bronks composition of air air breathed inair breathed out 79% 21% 0.03%
TRANSCRIPT
AirBy
Mr. Bronks
Composition of Air
Oxygen
Nitrogen
Carbondioxide
Air breathed in Air breathed out
79%
21%0.03%
Oxygen in Air
• The part of air that supports combustion or burning
• Used up by breathing so use in hospitals
• Also rusting or corrosion• Rockets carry their own
supply of Oxygen
Rocket Fuel?
Burning thingsWhen something is burned it reacts with oxygen. For example:
Magnesium + oxygen Magnesium oxide
Carbon + oxygen Carbon dioxide
Sulphur + oxygen Sulphur dioxide
The Fire Triangle
Fire
Fuel
Oxy
gen
Heat
Percentage of Oxygen
When we cover the candle the oxygen is used up – the water rises to fill the gap
We measure the rise and find it’s around 21%
Candle
Water
Gas Jar
Testing for carbon dioxide
Air
Limewater turns milky/cloudy
Limewater
Proves Carbon Dioxide in Air
Testing for Water Vapour in Air
Drops on the test tube
Ice and Salt
Cobalt Chloride Paper turns pink in the presence of water
CO2
Catalyst• A substance that speeds up a
chemical reaction but is not used up in the reaction. Here platinum is used as a catalyst in this catalytic converter.
CO2
CO
CO2
Catalyst• A substance that speeds up a
chemical reaction but is not used up in the reaction. Here platinum is used as a catalyst in this catalytic converter.
CO2
COCO2
Oxygen
• Catalyst speeds up reaction but is not used up – Manganese Dioxide
• Oxygen does not dissolve in the water
Test for Oxygen
• Relights a glowing splint
Oxygen
Test for Oxygen
• Relights a glowing splint
Burning Magnesium in Oxygen• Burns much brighter• In fact goes crazy-nuts-bright-and-
scary
Oxygen
• Very Bright Flame
Burning Magnesium in Oxygen
• White Powder remains- Magnesium Oxide
Burning Magnesium in Oxygen
• Add water
2MgO +H2O2Mg(OH)
Water
2MgO +H2O2Mg(OH)
Water
Red Litmus turns Blue colour proves liquid is a BASE
• Very Bright Flame• White Powder remains-
Magnesium Oxide
Burning Magnesium in Oxygen
Add water and Red Litmus paper turns Blue colour proves liquid is a BASE
Rusting also needs Oxygen
Just like the candle the steel rusts and oxygen is used up. The space is filled with water
Steel wool
Water
Gas Jar
2 weeks later
Rusted
Preventing Rusting
Metals needs water and oxygen to rust
Preventing Rusting
• Plating• Painting• Greasing• Dry• Galvanising
Summary
H/W
• P233• Q 1,2,3,4,5.