Alum: Analysis That Confirms Whether Its a Compound

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Analysis of Alum, AlK(SO₄)₂ •12H₂O
Purpose
The purpose of the experiment is to confirm whether the compound is Alum. Introduction
Percent composition is defined as part divided by whole multiplied by 100. Water of hydrogen is defined as the amount of water produced into a molecule prepared in an aqueous solution. Molecular formula indicates the actual numbers and type of atoms in a molecule (notes). Procedure

The procedure in this experiment is to determine melting point and mole ratio of hydrated water to anhydrous AlK (SO₄). Part 1. Data Table
| Trial #1| Trial #2|
Measured Melting Point| 98.6 degrees C| 95.3 degrees C|
Literature Melting Point| 92.5 degrees C| 92.5 degrees C|

Part 2. Data Table
Mass of crucible and cover| 24.86g|
Mass of crucible, cover and alum crystals| 26.799g|
Mass of alum crystals| 1.937g|
Mass of crucible, cover and alum after heating #1| 26.034g| Mass of crucible, cover and alum after heating #2| 25.837g| Mass of water driven off| 0.197g|
Mass of AlK(SO₄)₂| 0.975g|
Moles H₂O| 0.053g|
Moles AlK(SO₄)₂| 0.00378g|
Mole ratio| 14.021g|

In this experiment it was concluded that yes, the substance was Alum. There were two rials and both had the same conclusion. Post-lab questions
1. They must be cool before you can weigh them.
2. The characteristics were similar; therefore, it had to be alum. 3. Other tests like using a flame.
Conclusion
In this experiment we confirmed that the compound is Alum.
Vonderbrink, Sally A Laboratory Experiments for advanced placement chemistry. 2nd edition. Batavia: Flinn scientific, 2006. Print.
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