Chem Lab: Density of Aluminum
Name: ____________________________ Hour: _______
Purpose: Compare the density of two different forms of solid aluminum metal (aluminum strip and pellet)
Materials: Triple Beam Balance, Aluminum Strip, Metric Ruler, Aluminum Pellets, Graduated Cylinder, Water
Hypothesis: Which will have a greater density: the aluminum strip or the aluminum pellets? __________________
______________________________________________________________________________________
Trial #I: Determining the density of an aluminum strip (a uniform solid)
1) Make sure your balance is clean, dry and at zero.
2) Obtain an aluminum strip.
3) Using the balance determine the mass and record below. Report your answer to two decimals.
4) The thickness of the aluminum is 0.038cm. Record in the space below.
5) Using a ruler, determine the length and width of the aluminum strip in centimeters. Be sure to report your
answer to one decimal place.
Mass of aluminum strip
____________ Thickness of aluminum strip
Width of the aluminum strip
Length of aluminum strip
____________
____________
____________
Calculations:
1) Volume = Length X Width X Thickness (cm3). Using the data above, calculate volume and report your
answer to two decimal places—even if your last number is a zero! SHOW YOUR WORK FOR CREDIT.
2) Density = mass ÷ volume. Using the mass you measured and recorded above and the volume you calculated in
the above problem, determine the density of your aluminum strip in grams per cubic centimeter (g/cm3).
Report your answer to two decimal places. SHOW YOUR WORK FOR CREDIT.
**This is your answer for Trial #1**
Trial #2: Determining the density of aluminum pellets (a non-uniform solid)
1) Add 12-16 aluminum pellets directly on the balance pan.
2) Record the mass of the aluminum to two places after the decimal.
3) Add distilled water to a graduated cylinder until you have a volume right around 25 mL.
4) Record this initial volume of water to one decimal place.
5) Carefully, without splashing, add the pellets to the cylinder of water.
6) Read and record the final volume of water and pellets.
7) Pour out the water and put the aluminum pellets on a paper towel on your table. DO NOT DUMP PELLETS
INTO THE SINK.
Mass of aluminum pellets
____________ Volume of aluminum pellets + water
Volume of water only
Volume of aluminum pellets only
____________
-___________
____________
Calculations :
Chem Lab: Density of Aluminum
Name: ____________________________ Hour: _______
1) Calculate the density of the aluminum pellets in grams per cubic centimeter: Report answer to two
decimal places.
**This is your answer for Trial #2**
Comparing Density of Aluminum Strip vs. Aluminum Pellets
To do this we will calculate percent error for each trail. The smaller the percent error the closer your results are
to the accepted value. The formula we use to calculate this is:
% error = observed value – expected value
expected value
x
100
The observed value is what you calculated in Trials #1 and #2. The expected value for aluminum (strip and pellets)
is 2.70 g/cm3.
2) Calculate your percent error for Trial # I (aluminum strip). Show all work and report your answer to two
places past the decimal.
Trial #1 % error = Trial #1 Answer – 2.70 X 100 = _______________ %
2.70
3) Calculate your percent error for Trial #2 (aluminum pellets). Show all work and report your answer to two
places past the decimal.
Trial #2 % error = Trial #2 Answer – 2.70 X 100 = _______________ %
2.70
4) How close were you to the expected value of 2.70 g/cm3? Don’t say “close or not very close” state how close (#)
you were for EACH trial.
5) Which method were you closer to the expected value? Why do you think this is the case?
6) Suggest a way to improve your accuracy if you were to repeat this lab:
7) Was your hypothesis found to be correct? Explain.