Copy of Lab Report Week 2

Investigation 2: How is Glassware Used?

Introduction: This experiment was conducted to test the density of water in a variety of glassware. Density is the relationship between the mass of a substance and how much space it takes up. Water is a polar inorganic compound with a density of 1 g/cm^3. The first part of this experiment was measuring the density of water in a 50 milliliter beaker. Two trials were conducted with a 125 milliliter erlenmeyer flask, 100 milliliter beaker, and a 10 milliliter graduated cylinder in addition to the initial 50 milliliter beaker. The group predicted that when the mass of the water was calculated, the density could then be found. This experiment is important because accurately measuring the mass of a substance in a variety of glassware is crucial when conducting labs that require the precise measurement of liquid.

Results: Temperature of water: 21.2 degrees Tables represent the calculated measurements of the different types of glassware used; 50 ml beaker, 125 ml erlenmeyer flask, 50 ml burette, 10 ml graduated cylinder. Table 1: 50 ml beaker - Mass of empty 50 ml beaker: 28.567 g Trial Mass of 50ml beaker with water Mass of Water (g) Volume of water (ml) Experiment al Value of Density (g/ml) Percent error (%) 1 38.508 g 9.941 g 9.95 ml .999 g/ml .2 % 2 48.676 g 20.109 g 20.0 ml 1.005 g/ml .85% - Average Density (g/ml): 1.002 g/ml - Average Percent Error (%): 0.525 % Table 2: 125 ml erlenmeyer flask - Mass of empty 125 ml erlenmeyer flask: 81.704 g Trial Mass of 125 ml erlenmeyer flask Mass of water (g) Volume of water (ml) Experimental Value of Density (g/ml) Percent Error (%) 1 132.780 ml 51.076 g 50.0 ml 1.022 g/ml 2.46 % 2 107.946 ml 26.242 g 25.00 ml 1.056 g/ml 5.28 % - Average Density (g/ml): 1.036 g/ml - Average Percent Error (%): 3.87 % Table 3: 50 ml Burette - Mass of empty 50 ml burette: 51.945 g Trial Mass of 50ml Burette with water Mass of water (g) Volume of water (ml) Experimental Value of Density (g/ml) Percent Error (%) 1 68.361 ml 16.416 g 15.00 ml 1.094 g/ml 9.77 %

2 63.662 ml 11.717 g 15.00 ml .781 g/ml 21.73 % - Average Density (g/ml): .938 g/ml - Average Percent Error (%): 13.25 % Table 4: 10 ml graduated cylinder - Mass of empty 10 ml graduated cylinder: 27.226 g Trial Mass of 10ml graduated cylinder with water Mass of water (g) Volume of water (ml) Experimental Value of Density (g/ml) Percent Error (%) 1 38.708 ml 11.482 g 10.00 ml 1.148 g/ml 15.00 % 2 38.559 ml 11.333 g 9.98 ml 1.135 g/ml 13.72 % - Average Density (g/ml): 1.141 g/ml - Average Percent Error (%): 14.385 % Table 5: Density of water at Various Temperatures Temperature (C) Density (g/ml) 21.0 0.9979955 Calculations: Calculating the mass of water : (Mass of the glassware used with water) - (Mass of empty glassware) = Mass of water (g) Table 1 measurements (50 ml beaker): (38.508)- (28.567) = 9.941 Calculating the Density: D=m/V Table 1 measurements (50 ml beaker): (9.941)/ (9.95)= .999 Density = .999 g/ml

Discussion: The purpose of this lab was to practice measuring quantities of solid and liquid as well as learning what types of glassware is used for what specific task in lab. The results obtained are testaments to the accuracy of the measurements obtained using the specific types of glassware. Surprisingly, the most accurate measurements came from the 50 mL beaker and the least accurate from the 10 mL graduated cylinder. However, all measurements of volume were taken out of the same buret and should be accurate. Therefore, the source of error came from the measurements of weight. These discrepancies could have been caused by the scales themselves and their tendency to fluctuate in value while taking readings. These fluctuations could have led to improper readings for mass, leading to larger percent error as these measurements were used for calculations throughout the experiment. Further, due to time constraints as the result of a few group members arriving to lab unprepared, readings and measurements were hurried which can always lead to inaccuracy. Further, the portion of the lab relating to measuring the mass of a solid (sand) was not carried out due to the time restrictions. The statistical error increased as the lab went on, going from <1% on the first glassware to >14% on the last glassware measured. This upward trend in error, coupled with the increasing assumed accuracy of the glassware used, points to human error rather than equipment or calculation error. Relating these results back to main chemistry components and the purpose of the lab, it is abundantly clear that careful and precise measurements in addition to the use of correct glassware for the desired quantity and procedure is tremendously important to obtaining accurate and precise results.

Conclusion: In essence, through the experiment performed, the goal of learning what type of glassware to use for different specific tasks in the lab, was achieved. Having obtained data in performing the experiment, such as the volume and mass of the water to find its density, we found that different types of glassware give more accurate measurements than others. The use of the proper piece of glassware for a certain measurement is evidently important to obtain the most accurate results possible.