Density LabName:

Purpose: Students will: (1.) Determine the mass, volume, and density of metal pieces and an unknown liquid and (2.) Learn how to construct proper graphs of real data.

Safety: Use care when working with any material – including the various metal pieces!!! (Don’t stick any into your ears or nose!!)

Prelab Question:

______1. Is density an extensive or intensive property? Explain your answer:

______2. The volume of an unknown liquid is 15.0mL. The mass of the liquid and the graduated cylinder is 55.2g. If the mass of the graduated cylinder alone is 44.8g, what is the mass of the unknown liquid?

______3. What is the density of the liquid described in Problem #2? Solve using dimensional analysis (credit will not be given if dimensional analysis work is not shown).

______4. What is the volume, in cm3, of a 45.0 gram sample of copper? The density of copper is 8.92g/cm3. Solve using dimensional analysis (credit will not be given if dimensional analysis work is not shown).

______5. What is the mass, in g, of a 12.0 cm3 gram sample of aluminum? The density of aluminum is 2.70 g/cm3. Solve using dimensional analysis (credit will not be given if dimensional analysis work is not shown).

Procedure:

Record data in data tables. Make sure you take measurements and perform calculations using the correct number of significant digits – it is part of your grade!!

Part 1

  1. Obtain materials from front table. Look at the pieces of metal - we are going to call the orange/brown metal “Metal A” and the grey/silver metal “Metal B”. Use the electronic balance to mass each sample and record your answers in Data Table 1.
  2. Fill a graduated cylinder about half full with tap water. Record the initial volume of water. Slide the piece of “Metal A” into the graduated cylinder. Make sure the entire metal piece is submerged in the water. Record the final volume of water. Determine the volume of Metal A. Record your answer in Data Table 1.
  3. Repeat step 2 with “Metal B”.
  4. Calculate the densities of Metal A and B. Record your answers in Data Table 1.
  5. In Data Table 2you will record your data as well as the data from all other groups in the class. In Data Table 2your Lab Pair number is the number on the side of your tub of materials. Fill in your data in Data Table 2, then go to Mrs. Hodgson’s computer and electronically fill in your data. (Remember that your Lab Pair number is the number on your tub of materials.) Once everyone has put their data in the computer you need to record the data to complete your Data Table 2. Circle your name at the top of this page.
  6. Dry off both pieces of metal and the graduated cylinder.

Part 2

  1. Determine the mass of an empty and dry graduated cylinder. Record the mass in Data Table 3.
  2. Pour approximately 10 mL of “Liquid 1” into the graduated cylinder. Record the mass of “Liquid 1” and the graduated cylinder in Data Table 3. Do not pour out the liquid!!! Determine the exact volume of “Liquid 1” and record it in your Data Table 3.
  3. Pour out “Liquid 1” and repeat step 7 and 8 with “Liquid 2.” (Both are safe to pour down the drain.)

Calculate the densities of Liquids 1 and 2 and record in Date Table 3.

Part 3

  1. On a sheet of graph paper, using the class data from Data Table 2, plot a line graph relating mass and volume. The graph needs to take up most of the sheet of graph paper. Choose an appropriate scale based on the class data. You will plot your class data for Metal A and B on the same graph. Plot Metal A data in red and plot Metal B in green. Plot your mass on the vertical (or y) axis and volume on the horizontal (or x) axis.
  2. Use a ruler to draw a red best-fit line through plotted Metal A points and then use a ruler to draw a green best-fit line through plotted Metal B points. Note that not all of the points in a group will be on the best-fit line, however, approximately as many points should be above the line, as are below the line.
  3. Label the following on your graph: title, label each axis, units on each axis, appropriate/logical number scales on each axis, and key.
  4. Determine the slope of each line. To do this, choose any two points on the line and do rise/run. In the graph you plotted, rise/run is equal to mass/volume, which is the formula for density. Thus, the slopes of the lines you have drawn represent the densities of the metals you have examined! On your graph (next to each line) write down the density of each metal.

Data Table 1 - Metals
(Individual Data Calculations) / Metal A / Metal B
mass (g)
initial volume of water (mL)
final volume of water (mL)
volume of metal alone (mL)
density of metal (g/cm3)
Data Table 2 (Class Data: Mass and Volume of Metals)
Metal A / Metal B
Lab Pair / volume (cm3) / mass (g) / volume (cm3) / mass (g)
1
2
3
4
5
6
7
8
9
10
11
12
Data Table 3 - Liquids
(Individual Data Calculations) / Liquid #1 / Liquid #2
mass of dry graduated cylinder(g)
mass of graduated cylinder and liquid(g)
mass of liquid alone(g)
volume of liquid(mL)
density of liquid (g/mL)

Data Analysis and Conclusion Questions

______1. On your graph what was the slope (density) of your line for Metal A?

______2. On your graph what was the slope (density) of your line for Metal B?

Percent Error Problems(accepted value Metal A = 8.92 g/cm3) &(accepted value Metal B = 2.702 g/cm3)

______3. Calculate the percent error for Metal A using the density you calculated for your sample (Data Table 1) as the experimental value. Show work.

______4. Calculate the percent error for Metal B using the density you calculated for your sample (Data Table 1) as the experimental value. Show work.

______5. Calculate the percent error for Metal A using the density you calculated from the slope of the line on your graph as the experimental value. Show work.

______6. Calculate the percent error for Metal B using the density you calculated from the slope of the line on your graph as the experimental value. Show work.

______7. Which of the approaches used to calculate the densities of Metal A and B gave you the lowest percent error: calculating the density from the mass and volume measurements for a single sample or calculating the density by determining the slope of the graph of mass and volume data for a number of samples?

______8. Do you think that density can be used to identify a substance? Explain your answer.

Metal A is______Metal B is______9. Identify the metals used in this experiment by comparing their densities to the densities of some common elements listed on page 903 of your textbook.

______10. What was the volume of your Metal A. How many significant digits are in this value?

______11. Calculate the percent error for “Liquid 1”. Show work.

(accepted density value Liquid 1 = 1.00g/mL)

Density Lab Graph