Dec.9--Lab 4C [Formula of a Hydrate]

Equipments:

- pipestem triangle

- iron ring & stand

- Bunsen burner

- dry crucible

  

Procedure:

1.      Put on lab apron and safety goggles.

2.      Set up the pipestem triangle, iron ring, stand and Bunsen burner. The ring should be 5-6 cm above the burner. Place a clean and dry crucible on the triangle, and heat for 3 minutes to make sure it is dry.

3.      Weigh the crucible and record the mass in Table 1.

4.      Place hydrate into it until it is 1/3 full. Record the total mass of crucible and hydrate.

5.      Place the crucible on the pipestem triangle, and begin heating. Gradually increase the heat until the bottom of the crucible is a dull red. Maintain the temperature for 5 minutes.

6.      Turn off the burner and allow the crucible to cool for 5 minutes. Weigh and record the total mass.

7.      Reheat the crucible for 5 minutes to make sure there is no more water left. Cool it down and record the mass. Use the lower mass number between the first and second heat. (The difference should be no more than 0.03 g.)

8.      Add a few drops of water to the contents of the crucible. Note any changes that occur.