Experiment: To Determine the Empirical Formula of Magnesium Oxide.

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September 12, 2003

Experiment: To Determine the Empirical Formula of Magnesium Oxide

INTRODUCTION:

        The empirical formula is the simplest and lowest whole number ratio of the different atoms in a sample of compound. To work out the empirical formula, the value of moles of the different atoms in a compound is needed. Mole is just simply a unit used to measure the amount of atoms, just like how the unit “dozen” is used to measure things such as eggs. One mole is 6×10^23 atoms and this number is called the Avogadro number. The mole can be also defined as the number of atoms in exactly 12g of Carbon.

In this experiment, the magnesium will be heated and this magnesium will react with the oxygen in the air to form magnesium Oxide.

DIAGRAM:

METHOD:

  1. An empty crucible and its lid were weighed on an electrical balance. The mass of the crucible and its lid were recorded.
  2. The surface of the magnesium ribbon was scraped with emery paper to remove any magnesium oxide on the surface.
  3. The magnesium was coiled and placed in the crucible. Then the lid was replaced on the crucible, and the mass of the crucible with lid containing the magnesium was found. The mass was recorded.
  4. The safety goggle was worn. Then apparatus was setup as shown in the diagram. The magnesium was first heated with a small blue flame and after a several minutes with a roaring flame.
  5. Every few minutes, the lid of the crucible was lifted carefully with a tong to see if the magnesium had started to burn and also to left some air enter the crucible to make the experiment more efficient.
  6. When the magnesium had completely reacted, the crucible was heated strongly without the lid on for few minutes. Then, the crucible was placed on gauze for it to cool down.
  7. When the crucible cooled down so that one was able to hold it, the crucible with lid containing the magnesium oxide was measured. The mass was recorded.
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RESULTS:

QUANTATIVE RESULTS:

OUALATATIVE RESULTS:

  • White fume was coming out of the crucible, when the lid was lifted.
  • When the magnesium was first heated, the magnesium was glowing slightly orange, but it turned into a strong glow later.
  • Short after the magnesium had started to be heated, the magnesium turned black. However, as the reaction was beginning to finish, the magnesium became an ashy white color.

CALCULATIONS:

Mass of magnesium:

Mass of crucible and lid with magnesium –  Mass of empty crucible and lid

                35.74g                        –                     ...

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