How is Lab Glassware Used?
Luis Cervantes, Ruby Morales, Justin Oursler, Cole Von Roeder
Friday September 4, 2015 10:30 am
Kaitlyn Mandigo
Section L52

Introduction: The intention of this investigation was to find the most precise and/or accurate glassware. Precision is how close the measured values are to each other, and accuracy is how close the measured value is true to the value. To do this different laboratory glassware was used to measure out density of water. Density is the ratio of an object’s mass (grams) to its volume (mL or cm^3). Therefore once we knew the mass and volume of the water being used then the density was calculated using the following formula: Density = mass/volume

This calculated density was then be compared to the expected, theoretical density of water at the current temperature (°c) by using the following percent error formula:

% Error = (experimental-theoretical)/theoretical

Additionally, significant figure rules are used to ensure accuracy in this lab. With this information on all glassware, it was determined which lab glassware was the most precise and/or accurate. Procedure/Experiment: This experiment required many different kinds of glassware to be used in order to successfully carry out the experiment. The types of glassware and other tools used are as follows: 50mL beaker, buret, electronic balance, 125mL Erlenmeyer flask, 10mL graduated cylinder, pipet, thermometer, and sand.
In experiment 1, the accuracy of a 50mL beaker was tested. The clean beaker was first weighed on an electronic balance and the mass was recorded. For the first trial, 30mL of water was added to the beaker and then weighed again. That mass was recorded and then the mass of the water was recorded by subtracting the mass of the empty beaker from the mass of the beaker with the water. To find the experimental value of density in grams over milliliters, the mass of the water was divided by the volume of the water. Once the experimental value of density was determined, the percent error was calculated by subtracting that number by the theoretical number, divided by the theoretical, multiplied by 100. Theoretical is found by using looking for the temperature of the water used, stated in appendix J of the lab manual. Trials 2 and 3 are done following the same steps but changing the volume of the water to 20mL and 40mL.
In experiment 2, the accuracy of a 50mL beaker was tested with the help of a buret. The clean beaker was first weighed on an electronic balance and the mass was recorded. For the first trial, 10mL of water was added to the beaker after being measured in the buret and poured into the beaker and then weighed again. That mass was recorded and then the mass of the water was recorded by subtracting the mass of the empty beaker from the mass of the beaker with the water. To find the experimental value of density in grams over milliliters, the mass of the water was divided by the volume of the water. Once the experimental value of density was determined, the percent error was calculated by subtracting that number by the theoretical number, divided by the theoretical, multiplied by 100. Theoretical is found by using looking for the temperature of the water used, stated in appendix J of the lab manual. Trials 2 and 3 are done following the same steps but changing the volume of the water to 20mL and 30mL.
In experiment 3, the accuracy of a 125mL Erlenmeyer flask was tested. The flask was first weighed on an electronic balance and the mass was recorded. For the first trial, 50mL of water was added to the flask and then weighed again. That mass was recorded and then the mass of the water was recorded by subtracting the mass of the empty flask from the mass of the flask with the water. To find the experimental value of density in grams over milliliters, the mass of the water was divided by the volume of the water. Once the experimental value of density was determined, the percent error was calculated by subtracting that number by the theoretical number, divided by the theoretical, multiplied by 100. Theoretical is found by using looking for the temperature of the water used, stated in appendix J of the lab manual. Trials 2 and 3 are done following the same steps but changing the volume of the water to 75mL and 100mL.
In experiment 4, the accuracy of a 10mL graduated cylinder was tested. The dry, empty graduated cylinder was first weighed on an electronic balance and the mass was recorded. For the first trial, 1mL of water was added to the graduated cylinder drop by drop, with a pipet, and then weighed again. That mass was recorded and then the mass of the water was recorded by subtracting the mass of the empty graduated cylinder from the mass of the graduated cylinder with the water. To find the experimental value of density in grams over milliliters, the mass of the water was divided by the volume of the water. Once the experimental value of density was determined, the percent error was calculated by subtracting that number by the theoretical number, divided by the theoretical, multiplied by 100. Theoretical is found by using looking for the temperature of the water used, stated in appendix J of the lab manual. Trials 2 and 3 are done following the same steps but changing the volume of the water to 2mL and 3mL.

Results:
Mass (g), Volume (mL), and Density (g/mL) of Water Measured with 50 mL Beaker Mass of Empty, Dry 50 mL Beaker (g): 30.361 Theoretical = .9972995 Trial | Mass of 50mL Beaker w/ Water (g) | Mass of Water (g) | Volume of Water (mL) | Experimental Value of Density (g/mL) | Percent Error (%) | 1 | 57.4 | 27.1 | 30.0 | .903 | 9.38% | 2 | 46.4 | 16.1 | 20.0 | .804 | 19.3% | 3 | 68.6 | 38.2 | 40.0 | .957 | 4.02% | Average Density (g/mL): 0.889 Average % Error: 10.1%
Experimental Value of Density (g/mL): Mass of water/Volume of water-- 27.105/30=.9035

Mass (g), Volume (mL), and Density (g/mL) of Water Measured with a 50 mL Buret
Mass of Empty, Dry 50mL Beaker w/ Buret (g): 30.361 Theoretical= .9972995 Trial | Mass of 50mL Beaker w/ Water (g) | Mass of Water (g) | Volume of Water (mL) | Experimental Value of Density (g/mL) | Percent Error (%) | 1 | 39.9 | 9.57 | 10 | .957 | 3.95% | 2 | 49.6 | 19.2 | 20 | 0.963 | 3.43% | 3 | 59.4 | 29.1 | 30 | 0.971 | 2.66% |
Average Density (g/mL): 0.963 Average % Error: 3.35%
Experimental Value of Density (g/mL): Mass of water/Volume of water-- 9.579/10=.9579

Mass (g), Volume (mL), and Density (g/mL) of Water Measured with a 125 mL Erlenmeyer Flask
Mass of 125mL Erlenmeyer Flask (g): 89.21 Theoretical= .9975415 Trial | Mass of 125mL Erlenmeyer Flask (g) | Mass of Water (g) | Volume of Water (mL) | Experimental Volume of Density (g/mL) | Percent Error (%) | 1 | 132 | 43.3 | 50 | .867 | 13.0% | 2 | 160 | 70.9 | 75 | .946 | 5.16% | 3 | 185 | 96.5 | 100 | .965 | 3.21%% |
Average Density (g/mL): .926 Average % Error: 7.14%
Experimental Value of Density (g/mL): Mass of water/Volume of water-- 43.374/50=.86748

Mass (g), Volume (mL), and Density (g/mL) of Water Measured with a Graduated Cylinder
Mass of Empty, Dry 10mL Graduated Cylinder (g): 26.979 Theoretical= .9975415 Trial | Mass of Glassware w/ a Certain # of drop to reach 1mL (g) | Mass of Water (g) | Volume of Water (g) | Experimental Volume of Density (g/mL) | Percent Error (%) | 1 | 27.8 | .833 | 1 | .833 | 16.4% | 2 | 28.6 | 1.68 | 2 | .844 | 15.3% | 3 | 29.7 | 2.72 | 3 | .907 | 9.07% |
Average Density (g/mL): .861 Average % Error: 13.6%
Discussion:
The purpose of this lab was to find to accuracy and precision of the volumetric measuring equipment. Of the four measuring devices, the 50mL buret was the most accurate with a 3.35% error, the 125mL Erlenmeyer flask was the second most accurate with a 7.14% error, the 50mL beaker was the third most accurate with a 10.9% error, and the graduated cylinder was the least accurate with a 13.7% error. Using significant figures allowed for accurate calculations and consistent results that could have possibly affected the recorded results of accuracy and precision had they not been used. One source of error was the scale used to weigh the mass of the measuring device with and without water. The scale was very sensitive and would have a 5-10 milligram range of change in mass. Not using significant figures correctly was also an error in the lab. These errors could have been avoided by using as few significant figures as necessary. If 38 mL of water had to measured, the best measuring device in this situation would be the 50mL beaker since it is accurate enough to measure 38mL. If 38.50mL of water had to be measured, the best measuring device to use in this situation would be the 50mL buret as it measures more accurately than any of the other devices and is better suited for very precise volumes.

Conclusion: In this lab it was found that using a buret to measure water was the most precise and accurate way. This was concluded because the measurements done with the buret averaged out to have a lower percent error than that of the other pieces of glassware. This means that the experimental measurement was the closest to the theoretical measurement the most amount of times compared to those of the other glassware used. Overall, the approach used for this experiment was a successful application of finding the most precise and accurate glassware.

Work Cited: 1. Bauer, R., Birk, J., Sawyer, D. Laboratory Inquiry in Chemistry, 3rd ed.; Cengage Learning: Boston, 2015.