Oxygen And Oxides

Amounts Of Gases In Air
Nitrogen 78%
Oxygen 21%
Argon 1%
Carbon Dioxide 0.04%
Water Vapour varies
Burning Phosphorus in a bell jar
The phosphorus burns and reacts withe
the oxygen. As the oxygen is used up
it is replaced by water, which rises
1/5 up the bell jar
Preparing oxygen in the laboratory
Oxygen car be prepared by the catalytic decomposition of hydrogen peroxideHydrogen peroxide(2H2O2) decomposes into water and oxuygen gas
the decomposition only occurs very slowly but can be speeded up by using a catalyst
(Manganese Oxide)
Test for oxygen
Oxygen will relight a glowing splint
Properties of Oxygen
Oxygen is slightly soluble in water, which enables aquatic life to live
Oxygen is very reactive, but in air is diluted by very unreactive Nitrogen Gas
Uses of Oxygen
It is used as a breathing aid
When burned with Hydrogen gas is used as rocket fuel
When burned with acetylene(ethyne) it produces and hot flame(oxy-acetylene flame)
It is used to make steel from cast iron
Burning substances in Oxygen
Substances burn much better in oxygen than in air
Metal + Oxygen—–>Metal Oxide
None-metal + oxygen—–>Non-metal oxide
Testing for Acid Or alkaline
Ading universal indicator will turn:
Strong acid Red-Orange
Weak acid Orange-Green
Weak Alkali Green-Blue
Strong Alkali Blue-Purple
Magnesium when burned in Oxygen
Burns with a brilliant white flame, leaving a white ash(Magnesium Oxide) MgO will turn Universal indicator blue upon shaking
Sulfur when burned in Oxygen
Burns with a blue flame producing a colourless gas(Sulfur Dioxide)Turns Universal indicator red
Carbon when burned in Oxygen
Burns with a red glow and sparks producing a colourless gas (Carbon dioxide) which turns Universal indicator Orange
Sodium when burned in Oxygen
Burns with a golden yellow flame, producing a white solid (Sodium oxide) Turns Universal indicator Violet
None-metal oxides are acidic
Metal oxides are basic (i.e. dissolve in water to form alkaline solutions)
Acid Rain
Rain water is naturally slighlty acidic because of dissolved CO2. Non-metal oxides such as Sulfur dioxide make rain water more acidic.
Causes of Acid rain
Petrol engines in cars produce Oxides of nitrogen, such as NO or NO2. Because the spark makes nitrogen and oxygen react together
Problems of Acid Rain
Acid rain attacks metals and limestone
Acid rain has a devastating effect on tree growth
Acid rain alters the PH of lakes, threatening aquatic life
Preperation of Carbon dioxide
CO2 is prepared by reacting an acid with a carbonate.
CO2 can be collected by downward delivery or displacement of water because it is more dense than air
Reaction of limewater with CO2
Ca(OH)2 + CO2—–>CaCO3 + H2O

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