Hydrated Chloride
Purpose: The purpose of this experiment is to determine the number of moles of water molecules of crystallization of a sample of hydrated Barium
Chloride. This can be calculated using Gravimetric Analysis and to indirectly determine the percent composition of a hydrate by taking advantage of its chemical properties.
Introduction:
Gravimetric procedures are analytical methods in which the results are determined from the masses of starting materials and products. These methods differ from volumetric procedures in which the calculations are based on the volumes of standardized solutions used in the procedure. One of the simplest gravimetric procedures involves the heating of a weighed sample to drive off a volatile component. The difference in mass before and after heating provides the mass of the volatile component. Hydrates are examples of compounds that would display this behavior. If the formula of …show more content…
the hydrate is known, the percentage of hydrate in a mixture can be determined.
Equipment/Materials:
o unknown mixture analytical balance o crucible tongs o bunsen burner clay triangle
Caution:
• Wear eye Protection and if any chemical splashes in your skin wash it off immediately.
• Barium Chloride is harmful by inhalation and by ingestion or skin contact. Wear Gloves.
• Hydrated Barium Chloride is crystalline, but the anhydrous salt that is produced is powdery. Avoid raising a dust.
Procedure:
All absorbed moisture was removed from the empty crucible by heating on a pipe-clay triangle over a blue Bunsen burner flame for about 10 minutes and then the crucible was lifted with clean tongs and allowed to cool in a desiccator (which contained silica gel that absorbed moisture).
Once cool, the empty crucible was weighed and approximately 2-3g of Hydrated Barium Chloride was added to the crucible. The crucible and contents were then weighed on a balance and a note of the mass was taken. The crucible was then heated for 15minutes using a blue Bunsen burner flame on the pipe-clay triangle, with the lid partially covering the contents. The crucible was then transferred to the desiccator using tongs. Once cooled, the crucible + contents were re-weighed. This process was repeated, heating for about4 minutes each time, until two successive balances reading were within 0.002g of each other, at this point the contents were at constant mass, and all of the water had been removed. The value of n in BaCl2.nH2O was then
calculated.
Data and result: Consult the page attached to the report
Discussion:
The number of moles of water molecules of crystallization per mole of Hydrated Barium Chloride was calculated (the value of n in BaCl2.nH2O). The value could have been calculated more accurately by:
* Making sure that all water had definitely been removed from sample (more thorough in heating to constant mass).
* Making sure clean equipment was used.
* Possessing more accurate measuring equipment.
* Making sure a blue flame was used (as soot formation would affect readings)
Conclusion: The calculated values of 2.23 and 2.05 mole of water of crystallization were slightly higher than the actual value of 2 mol. the fact that in both attempts the final two mass readings are the same is indicative that the crucibles contents have reached constant mass, and the BaCl2 is therefore anhydrous.
Evaluation:-The slightly inaccuracy of the experiment could be attributed to soot forming on the crucible; this was minimized by using a blue flame from the Bunsen burner, which is less sooty than a yellow flame. If soot formed on the crucible its mess would be changed, making the results inaccurate.
Dirt could have been transferred from the tongs to the crucible while it was being lifted, again this would affect the mass of the crucible.
This error would have been eliminated had clean tongs been used.
The Barium Chloride had to be heated to constant mass to ensure that all traces of water had been removed to reduce errors in the calculation. Gravimetric analysis is more accurate than volumetric analysis because the only error in gravimetry should be weighing error so the results are as accurate as the balance used.
Improvements could have been made by using a more accurate balance and also by calibrating the balance.
Chloride. This can be calculated using Gravimetric Analysis and to indirectly determine the percent composition of a hydrate by taking advantage of its chemical properties.
Introduction:
Gravimetric procedures are analytical methods in which the results are determined from the masses of starting materials and products. These methods differ from volumetric procedures in which the calculations are based on the volumes of standardized solutions used in the procedure. One of the simplest gravimetric procedures involves the heating of a weighed sample to drive off a volatile component. The difference in mass before and after heating provides the mass of the volatile component. Hydrates are examples of compounds that would display this behavior. If the formula of …show more content…
the hydrate is known, the percentage of hydrate in a mixture can be determined.
Equipment/Materials:
o unknown mixture analytical balance o crucible tongs o bunsen burner clay triangle
Caution:
• Wear eye Protection and if any chemical splashes in your skin wash it off immediately.
• Barium Chloride is harmful by inhalation and by ingestion or skin contact. Wear Gloves.
• Hydrated Barium Chloride is crystalline, but the anhydrous salt that is produced is powdery. Avoid raising a dust.
Procedure:
All absorbed moisture was removed from the empty crucible by heating on a pipe-clay triangle over a blue Bunsen burner flame for about 10 minutes and then the crucible was lifted with clean tongs and allowed to cool in a desiccator (which contained silica gel that absorbed moisture).
Once cool, the empty crucible was weighed and approximately 2-3g of Hydrated Barium Chloride was added to the crucible. The crucible and contents were then weighed on a balance and a note of the mass was taken. The crucible was then heated for 15minutes using a blue Bunsen burner flame on the pipe-clay triangle, with the lid partially covering the contents. The crucible was then transferred to the desiccator using tongs. Once cooled, the crucible + contents were re-weighed. This process was repeated, heating for about4 minutes each time, until two successive balances reading were within 0.002g of each other, at this point the contents were at constant mass, and all of the water had been removed. The value of n in BaCl2.nH2O was then
calculated.
Data and result: Consult the page attached to the report
Discussion:
The number of moles of water molecules of crystallization per mole of Hydrated Barium Chloride was calculated (the value of n in BaCl2.nH2O). The value could have been calculated more accurately by:
* Making sure that all water had definitely been removed from sample (more thorough in heating to constant mass).
* Making sure clean equipment was used.
* Possessing more accurate measuring equipment.
* Making sure a blue flame was used (as soot formation would affect readings)
Conclusion: The calculated values of 2.23 and 2.05 mole of water of crystallization were slightly higher than the actual value of 2 mol. the fact that in both attempts the final two mass readings are the same is indicative that the crucibles contents have reached constant mass, and the BaCl2 is therefore anhydrous.
Evaluation:-The slightly inaccuracy of the experiment could be attributed to soot forming on the crucible; this was minimized by using a blue flame from the Bunsen burner, which is less sooty than a yellow flame. If soot formed on the crucible its mess would be changed, making the results inaccurate.
Dirt could have been transferred from the tongs to the crucible while it was being lifted, again this would affect the mass of the crucible.
This error would have been eliminated had clean tongs been used.
The Barium Chloride had to be heated to constant mass to ensure that all traces of water had been removed to reduce errors in the calculation. Gravimetric analysis is more accurate than volumetric analysis because the only error in gravimetry should be weighing error so the results are as accurate as the balance used.
Improvements could have been made by using a more accurate balance and also by calibrating the balance.