Chem+1+Unit+9+Lab

== =Unit 9 Lab: Hydrated Crystals=


 * Introduction**: Hydrates are compounds that incorporate water molecules in their crystalline structures. The ratio of moles of water to one mole of the compound is a small whole number. For example, in the hydrated compound copper II sulfate pentahydrate (CuSO4  5H2O), the ratio is 5:1. The ratio of moles of water to one mole of hydrate can be determined experimentally by heating the hydrate to remove water.


 * Objectives:**
 * Heat a known mass of hydrated compound until water is removed.
 * Calculate the formula for a hydrate using the mass of the hydrated compound and the mass of the anhydrous compound.


 * Materials:**
 * Bunsen Burner
 * Ring stand and ring
 * crucible and lid
 * Clay triangle
 * Crucible tongs
 * Balance
 * Epsom salts (hydrated MgSO4)
 * Spatula
 * Spark lighter

10.Wash crucible, lid and hands thoroughly
 * Procedure:**
 * 1) Measure to the nearest 0.01g the mass of a clean, dry crucible and lid. Record the mass.
 * 2) Add about 3 g hydrated MgSO4 to the crucible. Measure the mass of the crucible, lid, and hydrate to the nearest 0.01 g and record the mass.
 * 3) Record your observations of the hydrate
 * 4) Place the triangle on the ring of the ring stand. Carefully place the crucible in the triangle.
 * 5) Place the crucible lid on the crucible slightly slanted to one side to help prevent spattering and allow vapor to escape. Begin heating with a low flame, then gradually progress to a stronger flame. Heat for about 10 minutes.
 * 6) When heating is complete, remove the crucible using tongs. Place the lid on the crucible and allow the crucible and contents to cool.
 * 7) Measure the mass of the crucible, lid, and MgSO4 and record the mass in the data table. **//__Do not mass a hot crucible!!!__//**
 * 8) Observe the anhydrous MgSO4 and record your observations.
 * 9) Discard the anhydrous MgSO4 in the trash.


 * Data Table:**
 * **Mass Data and Observations of Epsom Salts** ||
 * Observations of hydrated MgSO4 ||  ||
 * Mass of crucible and lid ||  ||
 * Mass of crucible, lid and hydrate MgSO4 ||  ||
 * Mass of crucible, lid and anhydrous MgSO4 ||  ||
 * Observations of anhydrous MgSO4 ||  ||


 * Calculations Table:**
 * **Mass Calculations of Epsom Salts** ||
 * Mass of hydrated MgSO4 ||  ||
 * Mass of anhydrous MgSO4 ||  ||
 * Mass of water in hydrated MgSO4 ||  ||
 * Moles of anhydrous MgSO4 ||  ||
 * Moles of water in hydrated MgSO4 ||  ||
 * Ratio of anhydrous moles to moles of water ||  ||


 * Post Lab Questions:**
 * 1) Using your experimental data, calculate the formula for hydrated MgSO4. Please see section 9.4 example problems if you need help.
 * 2) How do appearances of the hydrated and anhydrous MgSO4 crystals compare? How are they different?
 * 3) If the hydrate’s formula is MgSO4  7H2O, what is the percent error for hydrated MgSO4? What are the possible sources of error? What procedural changes could you make to reduce the error?
 * 4) Predict the result of leaving the anhydrous crystals uncovered overnight. What would be different?