The Dehydration of a Bluestone

The Dehydration of a Bluestone

February.28.2008

Purpose

• To determine the value of X in CuSO4 • xH2O.

Materials

• Crucible

• Blue Stone

• Bunsen Burner

• Bunsen Lighter

• Test Tube

• Water

• Rheostat

• Clay Triangle

• Electronic Balance

Procedure

A clean crucible was taken and weighed on an electronic balance. The mass was then written down. 2g of bluestone was placed in the crucible and weighed. The mass of the blue solid was written down. The crucible was placed on a clay triangle and was heated by the Bunsen burner. When the blue color disappeared, the crucible was left to cool. After the crucible had cooled, the crucible was placed on the electronic balance to be weighed for its final mass of crucible and anhydrous solid. After the mass was written, a small amount of the anhydrous solid was taken and placed in a test tube. Then a few drops of water were added and the reaction was observed and written down.

Observations

Before

• The solid was in a blue solid crystal form.

During

• As it was heating, the blue solid slowly turned a whitish grayish color.

After

• The blue solid had turned a grayish white color and when water was added back to the anhydrous solid it turned blue again.

• When the water droplets were added the bottom of the test tube felt hot.

Data

Mass of Crucible 14.82 g

Mass of crucible and CuSO4 •xH2O 15.95 g

Mass of Crucible and anhydrous CuSO4 15.52 g

Calculations ------ Molar Mass of Copper Sulphate -> 64.0+32.1+16*4 = 160.1 g/mol

Mass of Crucible 14.82 g No Calculation

Mass of Crucible and Solid 15.95 g No Calculations

Mass of Crucible and Anhydrous Solid 15.52 g No Calculations

Mass of CuSO4 • xH2O 15.95 g – 14.82 g = 1.130 g 1.13 g

Mass of CuSO4 15.52 g – 14.82 g = 0.70 g 0.70 g

Mass of Water Lost 1.13 g – 0.70 g = 0.43 g 0.43 g

# of moles of CuSo4 15.52 – 14.82 = 0.70

0.70/160.1 = 0.044 mol 0.0044 mol

# of moles of Water 0.43 / 18 = 0.024 mol 0.024 mol

Amount of water per mol of CuSO4 0.024 mol / 0.0044 = 5.4 X = 5.4

Discussion

1. How do you know when the copper (2) sulphate has been converted to it anhydrous form?

• When