Chemistry lab: mass and volume measurements
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1. Determine the Accuracy and Precision of the Top-Loading Balance
b. Calculate the average weight of your standard mass as determined by the top-loading balance.
c. Calculate the percent error for each trial. Report your answers to three decimal places.
d. Calculate the average absolute deviation of your measurement. Report your answer to three decimal places.
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2. Volume Measurements with Common Glassware
a. 50 mL Beaker
Use the table of water density at different temperatures to find the density of water at 21.3 °C. Include all seven decimal places provided in the table. Use this density as the density of water for part a.
Answer – density of water at 21.3 °C is
Mass and volume measurements and calculations for three trials
| Trial 1 | Trial 2 | Trial 3 | |
| a.1. Mass of beaker with ~30 mL of water (g) | 56.10 | 62.36 | 60.30 |
| a.2. Mass of empty beaker (g) | 28.22 | 27.88 | 27.80 |
| a.3. Mass of water (g) | |||
| a.4. True volume of water in beaker, calculated from mass and density (mL) | |||
| a.5. Observed volume, as read from the beaker (mL) | 29 | ||
| a.6. Percent error reported to ONE decimal place | |||
a.7. Average percent error, reported to one decimal place
Taking the absolute values of the percent errors, then average percent error = (3.8+13.2+4.8)/3 =
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Normalized Observed Volume
| Trial 1 | Trial 2 | Trial 3 | |
| a.8. Normalized observed volume (mL) |
a.9. Average Vn =
a.10. Average absolute deviation, reported to one decimal place (calculated using Average Vn and three individual Vn values)
7Lab
b. 10 mL Graduated Cylinder
Use the table of water density at different temperatures to find the density of water at 22.9 °C. Include all seven decimal places provided in the table. Use this density as the density of water for part b.
Answer: density of water at 22.9 °C is
Measurements with a 10 mL Graduated Cylinder
Mass and volume measurements and calculations for three trials
| Trial 1 | Trial 2 | Trial 3 | |
| b.1. Mass of beaker with ~5 mL of water (g) | 32.96 | 33.07 | 32.44 |
| b.2. Mass of empty beaker (g) | 27.61 | 27.70 | 27.74 |
| b.3. Mass of water (g) | |||
| b.4. True volume of water in graduated cylinder, calculated from mass and density (mL) | |||
| b.5. Observed volume, as read from the graduated cylinder (mL) | 4.9 | 5.0 | 5.1 |
| b.6. Percent error reported to TWO decimal places | |||
b.7. Average percent error, reported to two decimal place
Taking the absolute values of the percent errors, then average percent error = (8.58+7.06+8.28)/3 =
Normalized Observed Volume
| Trial 1 | Trial 2 | Trial 3 | |
| a.8. Normalized observed volume (mL) |
a.9. Average Vn =
a.10. Average absolute deviation, reported to two decimal place (calculated using Average Vn and three individual Vn values)
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c. Buret
Use the table of water density at different temperatures to find the density of water at 21.9 °C. Include all seven decimal places provided in the table. Use this density as the density of water for part a.
Answer – density of water at 21.9 °C is
Mass and volume measurements and calculations for three trials
| Trial 1 | Trial 2 | Trial 3 | |
| c.1. Mass of beaker with ~10 mL of water (g) | 37.59 | 37.76 | 37.60 |
| c.2. Mass of empty beaker (g) | 27.63 | 27.81 | 27.61 |
| c.3. Mass of water (g) | |||
| c.4. True volume of water in beaker, calculated from mass and density (mL) reported to TWO decimal places | |||
| Final volume of water in the buret (mL) | 11.93 | 21.92 | 31.91 |
| Initial volume of water in the buret (mL) | 1.93 | 11.93 | 21.92 |
| c.5. Observed volume, as read from the buret (mL) | |||
| c.6. Percent error reported to TWO decimal places | |||
c.7. Average percent error, reported to two decimal place
Taking the absolute values of the percent errors, then average percent error = (0.2+0.2+0.2)/3 =
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Normalized Observed Volume
Calculation of normalized observed volume for three trials
| Trial 1 | Trial 2 | Trial 3 | |
| c.8. Normalized observed volume (mL) reported to TWO decimal places |
c.9. Average Vn =
c.10. Average absolute deviation, reported to three decimal place (calculated using Average Vn and three individual Vn values)
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3. Linear Relationships
Remember to report all of your answers using the correct number of significant figures.
Measurements for Successive Additions to a 10 mL Graduated Cylinder
Measurements for Successive Additions to a 10 mL Graduated Cylinder
| Total mass (g) | Observed Volume (mL) | Mass of water (g) | |
| Empty graduated cylinder | 27.59 | 0 | 0 |
| First addition | 29.71 | 2 | 2.12 |
| Second addition | 31.54 | 3.9 | 1.83 |
| Third addition | 33.7 | 6 | 2.16 |
| Fourth addition | 35.89 | 8.1 | 2.19 |
| Fifth addition | 38.04 | 9.8 | 2.15 |
Slope of best fit line
y-Intercept of best fit line
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4. Density of an Unknown Metal
Remember to report all of your answers using the correct number of signi6cant 6gures unless otherwise specified
Measurements of Unknown Metal Sample
Measurements of Unknown Metal Sample
| Trial 1 | Trial 2 | |
| a. Mass of dry metal sample (g) | ||
| Volume of water and metal sample (mL) | ||
| Volume of water (mL) | ||
| b. Volume of metal sample (mL) | ||
| c. Density of metal sample (g/mL) reported to ONE decimal place |
d. Average density of metal (g/mL), reported to one decimal place
e. Likely identity of metal (from table p.17) based on density and observations.
Copper
Questions
1. Which volume measuring device is the most accurate according to your results? Why?
2. Regardless of your results, beakers are not very reliable measuring devices, why use them in the lab?
3. From your plot of water mass versus volume, determine the slope of the best Pt line to the data. What does the slope represent here and how does it compare to the literature value for the same quantity?
