Skill Development & Grade Tracker

Volume Measurement Documentation:

Table of Recorded Data and Calculations For Volume Measurement:

Claim, Evidence, and Reasoning

Claim: I claim that as increments and diameter of glassware gets smaller, results of volume measurement get more accurate and precise. 

Evidence:  When calculating the percent error of each piece of glassware, the 100mL graduated cylinder had the lowest % error, while the 150mL medium beaker had the highest % error. The 100mL graduated cylinder had an experimental value of 49.48 mL while the 150 mL medium beaker had an experimental value of 42.94 mL. 

*see data table and percent error calculations above*

Reasoning: My claim stated that as increments and diameter of glassware gets smaller, results of volume measurement get more accurate and precise. From examining the evidence, we can clearly see a correlation between glassware increment/diameter size and accuracy/precision of measurements. The 150mL medium beaker had increments that were very distanced from each other; an entire 20 mL apart from one another. There wasn't even an increment line for which to measure the meniscus at the given actual value we needed to be measuring of 50 mL. This lack of measurement increments left us with an experimental value of 42.94 mL, which when compared to the actual value, left us with a whopping 14.12% percent error for the 150mL beaker. Compare this to the 100mL graduated cylinder, which had thin, tight increments at each mL value and a thin diameter. When using this piece of glassware, It was very easy to see where the meniscus reached the increment of 50mL, which allowed us to get an extremely close experimental value of 49.48 mL, which when calculated, left the graduated cylinder with a percent error of only 1.04%. This clearly shows that if a piece of glassware has thinner increments and a smaller diameter, it will produce more accurate and precise results than a piece of glassware with a large diameter and sparse increment lines. The percent error calculations are a clear indicator as to how trends in accuracy and precision are influenced by the variables stated.

Color Code Key:

• Claim: Blue

• Evidence: Green

• Reasoning: Yellow

Mass Measurement Documentation:

Claim, Evidence, and Reasoning

Claim:  I claim that group 4 had the most accurate set of beakers filled with white crystal.

Evidence: Group 4 had the lowest percent error average of our entire classroom. they had measurements of 129.08g for A, 129.24g for B, and 127.29g for C. The accepted value of mass of white crystals is 125g. they had a calculated 103.50g for the average mass of empty beakers D, E, F. Every other group (except for group 6) had a value similar to 103 for average mass of D, E, and F. 

Reasoning: With the evidence provided, we can determine that my claim that group 4 had the most accurate set of beakers filled with white crystal is correct. When looking at the average mass of empty beakers they used for their calculation of the mass of white crystal, they had the same value that every other group (with exception to group 6) had. This tells us that they accurately calculated the average mass of D, E, and F. With this calculation, they then calculated the mass of white crystal in each of the beaker's A, B, and C. after looking at their experimental values for each of the beakers, they are marginally close to the accepted value of 125g for the white crystal. This leads them to a percent error of only 2.83% when calculated. Comparing this percent error to every other group, we can conclude that they did accurately calculate all factors in this problem, which allowed them to discover that they had the most accurate set of white crystal beakers of the whole class.

Color Code Key: 

• Claim: Blue

• Evidence: Green

• Yellow: Reasoning

Lab Skills Demonstration:

This lab was a very interesting learning experience. I believe it allowed me to finally be able to determine the difference between accuracy and precision, which I realize now that I do find myself misusing both terms often. I demonstrated my skills of measurement by using eye-level viewings of meniscus, keeping surfaces stable and flat, and knowing which piece of glassware is most appropriate for any given situation in the lab. I also learned how averages and percentages are used to calculate unknown masses of substances within glassware and the accuracy/precision of mass calculations. I will continue to apply my newfound knowledge of accuracy vs. precision in any future lab sessions.