Magnesium Oxide

Summary

In this lab, you'll determine the empirical formula for magnesium oxide by combusting magnesium in an oxygen-rich environment. The experiment involves weighing a clean crucible, adding magnesium ribbon, and heating it with a Bunsen burner until it ignites. The reaction forms magnesium oxide, which is then processed by adding water to create a paste, followed by further heating. After cooling, the final mass of the crucible and product is recorded. The process teaches how to measure mass changes during a chemical reaction and deduce the empirical formula.

Takeaways

• 😀 Weigh the clean and dry crucible with its lid before adding magnesium to determine its mass.
• 😀 Ensure the magnesium ribbon weighs between 5 to 7.5 grams, and do not wrap it too tightly to allow air flow for combustion.
• 😀 Make sure all flammable materials, such as clothing or hair, are safely out of the way before lighting the Bunsen burner.
• 😀 Ignite the Bunsen burner by bringing a match or lighter near the gas flow once the gas is on.
• 😀 Position the Bunsen burner close enough to the crucible for effective heating, as high temperatures are necessary to ignite the magnesium.
• 😀 During ignition, raise the lid slightly to allow oxygen into the crucible, ensuring proper magnesium oxide formation.
• 😀 Do not look directly at burning magnesium due to the intense light that can harm your eyes.
• 😀 Ensure that oxygen enters the crucible throughout the reaction by either tilting or periodically raising and lowering the lid.
• 😀 Avoid excessive smoke, as it indicates loss of product; monitor the reaction until ignition stops.
• 😀 Once the reaction stops, turn off the Bunsen burner and allow the crucible to cool completely before proceeding.
• 😀 After cooling, use a medicine dropper to add water and stir the contents to form a paste before reheating to complete the formation of magnesium oxide.
• 😀 Once the reaction is complete and the material turns light gray, allow the crucible to cool and then weigh it again to determine the final mass.
• 😀 Clean the crucible thoroughly after the experiment to remove any residual solids and prepare it for future use.

Q & A

What is the purpose of this lab experiment?

The purpose of this lab is to experimentally determine the empirical formula for magnesium oxide by combusting magnesium in an oxygen environment.

Why is it important to clean and dry the crucible and its lid before weighing?

It is important to clean and dry the crucible and its lid to ensure accurate measurements of their mass and avoid contamination that could affect the results.

Why should the magnesium ribbon not be wrapped too tightly?

The magnesium ribbon should not be wrapped too tightly because air needs to get in for the reaction to take place. If it is too tightly wound, oxygen will not be able to reach the magnesium.

What is the role of the Bunsen burner in this experiment?

The Bunsen burner provides the heat necessary to ignite the magnesium. The high temperature causes the magnesium to combust in the presence of oxygen, forming magnesium oxide.

Why should you not look directly at burning magnesium?

You should not look directly at burning magnesium because the intense light can damage your eyes. It emits a very bright light during combustion.

What happens when the lid of the crucible is raised during the reaction?

Raising the lid of the crucible allows oxygen to enter, which is necessary for the magnesium to ignite and react with the oxygen to form magnesium oxide.

What is the significance of ensuring the reaction doesn't produce too much smoke?

If the reaction produces too much smoke, it indicates a loss of product, as some of the magnesium oxide may be escaping. It is important to minimize smoke to maximize the yield of the desired product.

What should be done once ignition ceases and the reaction is complete?

Once ignition ceases and the reaction is complete, the Bunsen burner should be turned off, and the crucible should be allowed to cool completely before proceeding to the next step.

Why is it necessary to add water to the solid magnesium oxide in the crucible?

Water is added to the solid magnesium oxide to turn it into a thick paste. This helps in completing the formation of magnesium oxide and allows for more efficient heating in the next step.

Why is it important to ensure that the crucible is completely cool before weighing it?

The crucible must be completely cool before weighing to avoid inaccurate mass readings caused by thermal effects or evaporation of any remaining water or volatile substances.