Chem 1211 Lab Report

Lexington Overstreet 9/14/2012
Title: Determination of Density of an Unknown Liquid
Unknown sample number P121736-LF12
First Combination of Equipment Employed 10 mL graduated cylinder, one decimal place balance.
Summary of Experimental Procedure A ten milliliter graduated cylinder was filled with the liquid so that the meniscus was exactly at the 10.0mL calibration mark. The liquid sample was then carefully poured into a clean, dry weighing vial which had been pre-weighed with its cap. The vial was capped, reweighed, and the density of the liquid computed using the formula: Density (g/mL) = Sample Weight (g)Sample Volume (mL)
This procedure was repeated three times.
Experimental Data Trial 1 Trial 2 Trial 3
Sample Volume 10 mL 10 mL 10 mL
Weight sample + capped vial 26.5g 26.5g 26.3g
Weight vial + cap 15.5g 15.4g 15.4g
Sample weight 11.0g 11.1g 10.9g

Calculated Results Trial 1 Trial 2 Trial 3
Density of samples: 1.10g/mL 1.11g/mL 1.09g/mL
Average density: 1.10g/mL 1.10g/mL 1.10g/mL
Deviation from Average: ±0.00g/mL ±0.01g/mL -0.01g/mL
Average Deviation: add absolute values of deviations from average and divide by the number of trials.
+0.00++0.01+-0.01= 0.02
∴ Therefore, the average deviation in density = ±0.02/3 = ±0.01
Average weight of 10mL Volume Samples
10mL x 1.1g/mL = 11g
Percent Inherent Error in Average Weight of Samples ±0.1 g/reading*2 readings 11* 100 = 1.8~2%
Percent Inherent Error in Average Volume of Samples ±0.1 mL/reading*1 readings 10 mL*100 = 1%
Total Percent Inherent Error in Density ±2%+ ±1%= ±3%
Inherent Error in Density 1.10g/mL x (±3/100) = ±0.03g/mL
Conclusions
Since the deviations from the average density are equal to or less than the total possible inherent error computed, it is concluded that the precision of the data collected was good.

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