Oxygen and oxides

• Oxygen in the laboratory is prepared by the catalytic decomposition of hydrogen peroxide (H2O2)
• hydrogen peroxide on its own decomposes to produce water and oxygen gas. It is made to decompose at a faster rate, if exposed to the light (u.v) as a result, hydrogen peroxide is stored in a dark brown bottle 


  2H2O2 (l) --> 2H2O (l) + O2 (g)
• To speed up the rate of the composition, a catalyst is used. The catalyst is manganese (IV) oxide (MNO2) 


  A catalyst is a substance that speeds up a realation without being used in the process
• What is missing?

  Beehive shelf

  
• Oxygen is slightly soluble. The solubility decreases as the temperature increases.
• In industry, oxygen is prepared by the fractional distillation of liquid air. 


  First air is passed through filters to remove dust particles. Then air is passed through sodaline to remove CO2. Then air is passed through carbonated sulfuric acid to remove water vapor. The remaining air is cooled to -200 at a pressure of 200 atm. Both nitrogen and oxygen are in liquid form. By slowly raising the temprature, to -190 nitrogen will boil off.
• The boiling point of nitrogen is -196
• The boiling point of oxygen is -183 degrees Celsius
• oxygen is used as an aid in breathing, as rocket fuel and in welding
• oxygen reacts with both metals and non metals to form oxides. Therefore oxides can be divided into metal oxides and non metal oxides
• Metal oxides can be basic oxides or amphoteric oxides
• A basic oxide is a type of metal oxide which reacts with dilute acids to produce salt and water


  Example

  MGO (s) + 2HCL (aq) --> MGCL2 (aq) + H2O (l)

  Basic oxide + dilute acid --> salt + water
• An amphoteric oxide is another type of metallic oxide which reacts with both dilute acids and alkali


  Example

  Aluminium oxide (Al2O3)

  Lead (II) oxide (pbo)

  Zine oxide (zno)
• AL2O3 (s) + 6HCL (aq) --> 2ALCL3 (aq) + 3H2O (l)

  Amphoteric oxide + dilute acid --> salt + water
• Not metal oxides can be either acidic oxides or neutral oxides
• Acidic oxides contain carbon dioxide. They react with water to form acids 


  Example

  CO2 (g) + H2O (l) --> H2CO3 (aq) Carbonic acid
• An acidic oxide can be Nitrogen dioxide 


  2NO2 (g) + H2O (l) --> HNO2 (aq) + HNO3 (aq)

  nitrous acid + nitric acid
• An acidic oxide can be sulfur dioxide 


  SO2 (g) + H2O (l) --> H2SO3 (aq) Sulfurous acid
• An acidic oxide can be sulfur trioxide 


  SO3 (g) + H2O (l) --> H2SO4 (aq) Sulfuric acid
• Neutral oxides are another type of non metal oxides. Neutral oxides do not dissolve in water 


  Neutral oxides can be :

  1. Carbon monoxide

  2. Nitrogen monoxide

  3.Dinitrogen oxide

  4.water
• Allotropes are different forms of the same element which can exist under the same conditions of temprature and pressure but have a different arrangement of atoms. 


  ,
• Oxygen has the allotrope ozone. Oxygen can be converted to ozone by passing the gas through an electrical spark


  3O2 (g) --> 2O3 (g)

  Spark