air and rusting

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air and rusting
2011-04-22 18:21:35
composition air nwhy do things rust

basics about the atmosphere and rusting
Show Answers:

  1. The earth's atmosphere has been the same for the past how many years?
    200 million
  2. What is the approximate composition of the air ?
    • 79% nitrogen (N in the periodic table)
    • 20% oxygen (O in the periodic table)
    • 1% other gases (including Argon [Ar], Carbon Dioxide [CO2], and water vapour)
  3. In an experiment, a pupil burnt 2.00g magnesium ribbon in air. He found that the mass of the powder formed was 2.80g. Explain this.
    The magnesium combines with the oxygen in the air to form the compound Magnesium Oxide which is heavier than magnesium due to the additional mass of the oxygen element.
  4. What is the name of the compound that we call rust
    • Iron oxide (Fe2O3).
    • Rusting is common because iron combines very easily with oxygen.
    • Rusting is an example of corrosion.
  5. Name the two main approaches to protect against rusting
    • 1. Barrier method : this is the most common method. It consist in protecting the iron by a layer (called a barrier) of paint, plastic, grease, or an unreactive metal such as tin or copper.
    • 2. Sacrificial Protection : the iron is actually covered by a more reactive metal such as Zinc (galvanization) which will "sacrifice" itself by corroding first, therefore protecting the iron.
  6. Write the word equation for the reaction that takes place when magnesium burns in oxygen
    Mg + O = MgO