Post by Admin on Nov 24, 2016 9:58:51 GMT
Air
Air consists of 78% nitrogen, 21% oxygen, <1% argon, 0.03% carbon dioxide, and 0-4% water vapour.
Air is a mixture. This is shown by the fact that its composition varies (e.g. there is less oxygen in the upper atmosphere).
Preparing Oxygen & Carbon Dioxide
Oxygen is prepared by the breakdown of hydrogen peroxide using manganese dioxide as a catalyst.
2H2O2 + MnO2 -> 2H2O + O2.
Carbon Dioxide is prepared by the reaction between hydrochloric acid and marble chips.
2HCl + CaCO3 -> CaCl2 + CO2 + H2O.
Tests
Carbon dioxide is tested for by passing it through limewater. It turns limewater milky.
Oxygen is tested for using a glowing splint - it relights a glowing splint.
Water is tested for using cobalt chloride paper. It turns from blue to pink in the presence of water.
Properties of Oxygen
Physical Properties: Colourless, odourless, tasteless, heavier than air, slightly soluble in water.
Chemical properties: Supports combustion, very reactive, neutral pH.
Properties of carbon Dioxide
Physical Properties: Colourless, odourless, tasteless, heavier than air, moderately soluble in water.
Chemical properties: Does not support combustion, turns limewater milky, forms an acid in water (called carbonic acid).
Uses of Oxygen
Breathing
Burning
Welding
Uses of Carbon Dioxide
Photosynthesis
Dry ice
Fizzy drinks
Air consists of 78% nitrogen, 21% oxygen, <1% argon, 0.03% carbon dioxide, and 0-4% water vapour.
Air is a mixture. This is shown by the fact that its composition varies (e.g. there is less oxygen in the upper atmosphere).
Preparing Oxygen & Carbon Dioxide
Oxygen is prepared by the breakdown of hydrogen peroxide using manganese dioxide as a catalyst.
2H2O2 + MnO2 -> 2H2O + O2.
Carbon Dioxide is prepared by the reaction between hydrochloric acid and marble chips.
2HCl + CaCO3 -> CaCl2 + CO2 + H2O.
Tests
Carbon dioxide is tested for by passing it through limewater. It turns limewater milky.
Oxygen is tested for using a glowing splint - it relights a glowing splint.
Water is tested for using cobalt chloride paper. It turns from blue to pink in the presence of water.
Properties of Oxygen
Physical Properties: Colourless, odourless, tasteless, heavier than air, slightly soluble in water.
Chemical properties: Supports combustion, very reactive, neutral pH.
Properties of carbon Dioxide
Physical Properties: Colourless, odourless, tasteless, heavier than air, moderately soluble in water.
Chemical properties: Does not support combustion, turns limewater milky, forms an acid in water (called carbonic acid).
Uses of Oxygen
Breathing
Burning
Welding
Uses of Carbon Dioxide
Photosynthesis
Dry ice
Fizzy drinks