Lab - As Dense as a Penny PDF

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This was alab for the penny thing and the lab...

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Name: _______________________________________________________Date:____________________Period:_______

Chemistry – Lab: As Dense as a Penny Background: Density is defined as the ratio of mass to volume, and its formula is density = mass / volume. The units for mass are grams (g). The units for volume are either cubic centimeters (cm3) or milliliters (mL), so the units for density can either be g/cm3 or g/mL. Density is physical property that can be used to identify an unknown substance. It is also considered an intensive property; that is, the density of an object does not depend on how much of the substance is present. For example, the density of water is 1.00 g/mL. Whether you have a drop, a glass, or a bucket of water… its density is always 1.00 g/mL. Over 2000 years ago King Hieron of Syracuse suspected that the jeweler who made his gold crown had mixed the gold with another cheaper metal. Although the kind could measure the mass of the crown, its intricate design prevented the measurement of its volume. King Hieron hired Archimedes, a Greek mathematician, physicist, and engineer to solve his dilemma. Archimedes knew that in order to solve the problem, he had to calculate the density of the crown and match it to the density pure gold. While taking a bath, Archimedes noticed the water level rise as he lowered himself into the tub and knew he had the solution. He could find the volume of the crown by measuring how much water it moved or displaced. Today, we know this as water displacement. Archimedes was so excited about his great discovery that he ran through the streets of Syracuse naked “Eureka!” Eureka is Greek for “I have found it.” Using the mass and volume of the crown, he calculated the density of the crown. The crown was indeed a fake. Archimedes was a hero! Objective: In this lab, you will measure the mass and volume of sets of pennies: pre-1982 pennies and post-1982 pennies. You will then graph the data, calculate the slope of the lines, and determine the density of the pennies. Materials: Balance, 25 pre-1982 pennies, 25 post-1982 pennies, graduated cylinder, tap water, massing boat, paper towels Procedure: 1. Place the massing boat on the balance. Press “Zero” to zero the balance. 2. Place 5 pre-1982 pennies in the massing boat. Record this value with units as “Mass” in Trial 1 in your data table. 3. Place 5 more pre-1982 pennies in the massing boat. Record this value with units in your data table. 4. Repeat steps 2 & 3 for Trials 2-5 until you have mass data for 25 pennies recorded in your data table. 5. Place 20.0 mL of tap water in the graduated cylinder. 6. Record volume value with units as your “Initial Volume” on Trial 1. 7. Place 5 pre-1982 pennies in the graduated cylinder. Record value with units as your “Final Volume” on Trial 1. a. Remember your guessed number when measuring!! b. Read the graduated cylinder at eye-level and at the meniscus. c. Slide the pennies into the graduated cylinder gently; avoid splashing any water onto the sides of the graduated cylinder. d. Tap the graduated cylinder to eliminate any air bubbles that may have formed between pennies. e. Leave the pennies in the graduated cylinder.

Name: _______________________________________________________Date:____________________Period:_______ 8. The “Initial Volume” should remain 20.0 mL for every trial. 9. Repeat step 6 by adding 5 pennies for Trials 2-5 until you have volume data for 25 pennies recorded in your data table. 10. Repeat steps 1-9 for the post-1982 pennies. Calculations: Record the following calculations in both data charts. 1. Calculate the “Volume of Pennies” for each trial by using the following formula: 𝑉𝑜𝑙𝑢𝑚𝑒 𝑜𝑓 𝑃𝑒𝑛𝑛𝑖𝑒𝑠 = 𝐹𝑖𝑛𝑎𝑙 𝑉𝑜𝑙𝑢𝑚𝑒 − 𝐼𝑛𝑖𝑡𝑖𝑎𝑙 𝑉𝑜𝑙𝑢𝑚𝑒. 2. Record the “Volume of Pennies” with units for each trial on both data charts. 3. On your data charts calculate the “Density of Pennies” for each trial by using the following formula: 𝑀𝑎𝑠𝑠 𝑜𝑓 𝑃𝑒𝑛𝑛𝑖𝑒𝑠 𝐷𝑒𝑛𝑠𝑖𝑡𝑦 = 𝑉𝑜𝑙𝑢𝑚𝑒 𝑜𝑓 𝑃𝑒𝑛𝑛𝑖𝑒𝑠 4. Record the “Density of Pennies” with units for each trial on both data charts. Since you are dividing mass by volume, your derived unit will be g/mL. 5. Calculate the average density of the Pre-1982 pennies and record this value with units in both data charts. 6. Calculate the average density of the Post-1982 pennies and record this value with units in both data charts. Graphing: Complete the graph according to the following: 1. Label the x-axis “Volume.” 2. Make a number line on x-axis that will best represent your data for volume. 3. Label the y-axis “Mass.” 4. Make a number line on the y-axis that will best represent your data for volume. 5. Title your graph according to y-axis VS. x-axis. 6. Using a colored pencil, plot the points for the Pre-1982 pennies. And connect the points with a “best fit line.” 7. Using a colored pencil of a different color, plot the points for the Post-1982 pennies. And connect the points with a “best fit line.” 8. Record on the chart the slope of each line. Calculate the slope of each line by using the formula below: ∆𝑦 𝑠𝑙𝑜𝑝𝑒 = ∆𝑥

Name: _______________________________________________________Date:____________________Period:_______ Name: __________________________________________________________________________________________

Chemistry–Lab: As Dense As a Penny – Pre-Lab **COMPLETE ON CANVAS ASSIGNMENT, NOT HERE!! 1. Define density. __________________________________________________________________________________ 2. What is the formula for density? ____________________________________________________________________ 3. What are the units for density? _____________________________________________________________________ 4. What two variables will be measured in this lab? ______________________________________________________ 5. What is to be done right after the massing boat is placed on the balance? __________________________________ _______________________________________________________________________________________________ 6. How many pennies are used in Trial 1? ______________________________________________________________ 7. What is the “Initial Volume” on Trial 1? ______________________________________________________________ 8. How is the last digit obtained in all the volume measurements? __________________________________________ ______________________________________________________________________________________________

Name: _______________________________________________________Date:____________________Period:_______

Chemistry - As Dense as a Penny - Data Charts Data charts: Include all units.

Pre-1982 Pennies Trials

Number of Pennies

Mass

Final Volume

Initial Volume

Volume of Pennies

Density of Pennies

1

2

3

4

5 Average Density of Pre-1982 Pennies

Post-1982 Pennies Trials

Number of Pennies

Mass

Final Volume

Initial Volume

Volume of pennies

1

2

3

4

5 Average Density of Post-1982 Pennies

Density of pennies

Name: _______________________________________________________Date:____________________Period:_______

Chemistry – Lab: As Dense As a Penny – Graph Title of Graph: _____________________________________________________________________________________

Show work for slope calculation: Pre-1982 pennies:

Post-1982 pennies:

Name: _______________________________________________________Date:____________________Period:_______

Chemistry–Lab: As Dense As a Penny – Analysis Answer the following questions about your data and calculations. 1. For the Pre-1982 Pennies, compare the “Density of Pennies” results for Trials 1-5. How are the results different? How are the results alike? Use at least two complete sentences to answer.

2. For the Post-1982 Pennies, compare the “Density of Pennies” results for Trials 1-5. How are the results different? How are the results alike? Use at least two complete sentences to answer.

3. Given your data, what overall conclusion can you make about the composition of the two sets of pennies? Answer in complete sentences.

4. Based on your data, which of the elements below is used in the Pre-1982 pennies and in the Post-1982 pennies? Answer in complete sentences to the left of the chart. Element Density Al 2.70 g/mL Cu 8.96 g/mL Fe 7.86 g/mL Ni 8.90 g/mL Ti 4.50 g/mL Zn 7.14 g/mL Zr 6.49 g/mL

5. What does the slope of the “best fit lines” represent on the graphs?

Name: _______________________________________________________Date:____________________Period:_______ 6. If copper is valued at $8.69 per 100.0 grams, what is the value of the copper in the twenty-five Pre-1982 pennies? Show work.

7. Using the accepted value for cooper from the above chart, your “Average Density of Pre -1982 Pennies” from your data chart and the formula below - calculate your Error for the “Density of Pennies.” Show work. 𝐸𝑟𝑟𝑜𝑟 = |𝑒𝑥𝑝𝑒𝑟𝑚𝑒𝑛𝑡𝑎𝑙 𝑣𝑎𝑙𝑢𝑒 − 𝑎𝑐𝑐𝑒𝑝𝑡𝑒𝑑 𝑣𝑎𝑙𝑢𝑒|

8. Using your Error answer from the above problem, calculate your Percent Error. Show work. |𝐸𝑟𝑟𝑜𝑟| × 100 𝑃𝑒𝑟𝑐𝑒𝑛𝑡 𝐸𝑟𝑟𝑜𝑟 = 𝐴𝑐𝑐𝑒𝑝𝑡𝑒𝑑 𝑉𝑎𝑙𝑢𝑒...