Researcher

Imran Husain

Objective

Calculating the density of cinnamic acid in a methanol solution at 0.25, 0.5, and 0.75 M in order to determine the accuracy of the method. The experiment will be done in both a 1 ml and 10 ml volumetric flask. The additivity of volumes is an assumption and the density of the solid is obtained from ChemSpider prediction.

Results

ONSC-EXP169Sheet1 calculations of solute mass
ONSC-EXP169Sheet2 measured density

Discussion

The percent error observed in the measured concentration of solution was found to be lower in the 10 ml volumetric flask than the 1 ml volumetric flask. Most values were within a 15% error range. Sample 3 alone showed a large error value of 68% most likely do to human error while combining the solute and solvent. The observed solution density was close to the accepted solvent density values in all samples. The cinnamic acid did not dissolve in methanol easily and required significant shaking and vortexing.
[Good analysis - compare to EXP170 as well JCB][Nice Work -AL]

Conclusion

Density and concentration calculation require precise measurement of chemical components. Percent error in molar concentration is greatly affected by mistakenly dropping even a small quantity of cinnamic acid. Also, concentration values seem to show less error witin a larger sized volumetric flask than a smaller one.

Log

2010-07-09

9:30 - Both 1 ml and 10 ml empty volumetric flasks were weighed and had their mass recorded within spreadsheet 2.
9:38 - Sample 1 was prepared with 1 ml of methanol transferred into 1 ml volumetric flask by glass pippet and then weighed and recorded.
9:51 - Sample 2 was prepared by adding 37.2 mg of cinnamic acid into the1 ml volumetric and a volume of methanol resulting in 1ml of solution and weighed.
10:05 - Sample 3 and 4 were prepared in the same manner as sample 2 within the 1ml volumetric flask with 74.4 mg and 111.5 mg of cinnamic acid relatively and weighed.
10:36 - Sample 5 was prepared with 10 ml of methanol transferred into 10 ml volumetric flask by glass pippet and then weighed and recorded.
10:47 - Sample 6 was prepared by adding 370.6 mg of cinnamic acid into the10 ml volumetric and a volume of methanol resulting in 10ml of solution.
11:08- Sample 7 and 8 were prepared in the same manner as sample 6 within the 10ml volumetric flask with 741.0 mg and 1111.8 mg of cinnamic acid relatively and weighed.