If we were doing the lab in person, we would need to prepare the crucible. Please read through the "Crucible Preparation procedure" below. You will not need to do this part, but there are post lab questions that relate to this process.
Crucible Preparation: The final results of this lab are dependent on getting accurate masses of the hydrate before and after it is dehydrated. In an analytical investigation that involves crucibles, the crucibles must first be cleaned from impurities. Even oils from your fingers as you touch the crucible can cause inaccurate masses. The typical process to clean a crucible is to heat it to constant mass, during which the impurities are burned away.
1. Set up the ring stand with ring clamp, clay triangle, crucible, and burner.
2. Adjust the height of the ring so it will be only a few inches above the top of the burner. With the burner off to the side, light the burner and adjust it to a proper heating flame. (A yellow-orange flame will produce soot on the crucible and counter the process of burning away the impurities.)
3. Place the burner under the crucible, lining up the inner cone with the bottom of the crucible and heat it vigorously for 5 minutes.
4. Turn off the burner and allow the crucible to cool. Only use the crucible tongs to touch/move the crucible from this step forward.
5. Once the crucible has cooled enough that no heat is detected with the back of your hand, carefully carry it to the analytical balance and find the mass of the empty crucible.
6. Repeat the heating and massing steps with the crucible until the masses of two successive heatings match.
1. Record the initial mass of the hydrate in the data table below.
2. Start heating the sample
3. Record the final mass of the dehydated sample in teh data table below.