Exp173

=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 conducted using a 10 ml volumetric flask. Samples from the experiment will also be analyzed with quartz-crystal microbalance density analysis in Dr. Lec's lab for comparison. The additivity of volumes is an [|assumption] and the density of the solid is obtained from ChemSpider prediction. =Results= [|Sheet 1 (solute mass calculation)] [|Sheet 2 (measured density calculation)] =Discussion= The method to determine the density using a 10 ml volumetric flask provided low percent error. It is a viable and efficient method for density determination in this instance. The highest error noted was that of 21%. The percent error is higher than the error noted for the 10 ml volumetric flask used in experiment Exp 169. This is most likely due to human error in creating the solutions. For example all cinnamic acid may not have entered the flask and went unnoticed. Also the scale used to measure the mass of the solute and solution showed an unusual range of fluctuation of a mg while measuring. This did not contribute to the entire percent error but did play a role. **[The results from the QCM are still pending but what can you say about the density method in this experiment in terms of error and how does it compare with previous experiments? JCB]** =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. Different methods provide different levels of accuracy. In comparison the two methods used to determine the density of cinnamic acid...

=Log=

2010-07-23
11:45- An empty 10 mL volumetric flask was wiped with a Kim wipe to ensure a dust free surface and then weighed 11:50- Sample 1 was created and weighed using the solute mass determined in Sheet 1. 11:53- Sample 1 was transferred into 20ml screw top test tube 11:54- Sample 2 was created and weighed using the solute mass determined in Sheet 1 (vortexing was required to break up cinnamic acid on bottom of flask) 11:59- Sample 2 was transferred into 20ml screw top test tube 12:17- Sample 3 was created and weighed using the solute mass determined in Sheet 1. (vortexing was required to break up cinnamic acid on bottom of flask) 12:20- Sample 3 was transferred into 20ml screw top test tube 12:26- Sample 4 was created and weighed using the solute mass determined in Sheet 1. (vortexing was required to break up cinnamic acid on bottom of flask) 12:30- Sample 4 was transferred into 20ml screw top test tube 13:40- Samples 1-4 were transported to Dr. Lec's lab for quartz-crystal microbalance analysis.