Lab density

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Name: ______________________________ Period: _____ Date: _______________
Lab: Density of an Unknown Solid
Problem: How do you determine the identity of a substance using the density of the solid?
Objectives:
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Students will calculate and measure the volumes of unidentified cylinders
Students will measure the masses of unidentified cylinders
Students will calculate the densities of unidentified cylinders
Students will use calculated densities to identify the cylinders’ elements.
Students will compare their calculated densities to the given density values and calculate the error and percent
error.
Students will plot the relationship between atomic number and density to determine if there is a density trend in
the perioidic table
Students will plot the relationship between atomic mass and density to determine if there is a relationship between
them.
Equations:
Density = mass / volume
Volume of cylinder; v = πr2h
Error = Accepted Value – Calculated Value
Percent Error = (Accepted Value – Calculated Value) / Accepted Value
Hypothesis:
1.) Can you determine the identiy of an unknow metal from its density? Why or Why not?
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2.) Will the densities you determine be within 10% error to the accepted values? Why or Why not?
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Procedure:
1. Obtain the four metal cylinders and record their physical description in the table below
2. Measure the mass of each cylinder and record it in the table below
3.Fill a PLASTIC 100 mL graduated cylinder with 50 mL of water. Record this as your INITIAL water volume. If
you have more or less than 50 ml, record your exact initial volume in ml.
4. Convert the volumes from ml to cm3. Record the cm3 value in the space below
5. Gently slide the first metal cylinder into the graduated cylinder and read the volume of water. Record this as
your FINAL water volume in ml. Then convert it to cm3.
6. Calculate the displacement of the water (the CHANGE in water level.) This is the VOLUME occupied by the
metal cylinder. Record this value in cm3.
7. Dry the metal cylinder and measure its radius and height in cm. Round to the nearest 0.1 cm. Record this in the
space below. Then place the cylinder back in the bag.
8. Repeat steps 3-7 for each of the four cylinders.
9. Calculate the densities for each of the four cylinders both with you measured volume and you calculated volume.
10. Compare the densities you calculated to the accepted values table. Identify the unknown samples using the
value that most closely matches the one you calculated.
Name: ______________________________ Period: _____ Date: _______________
Results
Cylinder
Physical
Description of
Cylinder
Mass in grams
Initial Volume of
Water in ml
Final Volume of
Water in ml
Initial Volume of
Water in cm3
Final Volume of
Water in cm3
Water
Displacement in
cm3
Volume of Cylinder
Measured in cm3
Radius of Cylinder
in cm
Height of Cylinder
in cm
Volume of Cylinder
Calculated in cm3
Density with
measure volume
Density with
calculated volume
Identity of
unknown cylinder
based on density
Error
Table density –
calculated density
Percent error
Error/ Table
Density
A
C
L
Z
Name: ______________________________ Period: _____ Date: _______________
Element
lithium
beryllium
boron
carbon
sodium
magnesium
aluminum
silicon
potassium
calcium
scandium
titanium
vanadium
chromium
manganese
iron
cobalt
nickel
copper
zinc
gallium
germanium
rubidium
strontium
silver
cadmium
indium
tin
cesium
barium
platinum
gold
mercury
thallium
lead
Atomic
Number
3
4
5
6
11
12
13
14
19
20
21
22
23
24
25
26
27
28
29
30
31
32
37
38
47
48
49
50
55
56
78
79
80
81
82
Density Atomic
mass
0.53
1.85
2.34
2.26
0.97
1.74
2.7
2.33
0.86
1.55
2.99
4.54
6.11
7.19
7.44
7.874
8.9
8.9
8.96
7.13
5.91
5.32
1.532
2.54
10.5
8.65
7.31
7.31
1.87
3.59
21.45
19.3
13.55
11.85
11.35
6.941
9.01218
10.811
12.011
22.98977
24.305
26.98154
28.0855
39.0983
40.078
44.9559
47.88
50.9415
51.996
54.938
55.847
58.9332
58.6934
63.456
65.39
69.723
72.61
85.4678
87.62
107.868
112.41
114.82
118.71
132.9054
137.33
195.08
196.9665
200.59
204.383
207.2
Discussion questions: Answer all questions on a separate sheet
of loose leaf and attach it to this lab. Graphing question should
include a graph drawn on the graph paper provided.
1. Why is density considered an intensive property and
volume and mass are considered extensive properties?
2. Was there a difference in the volume you measured with
the graduated cylinder and the one you determined using
geometry? If so what would account for those differences?
3. Did the cylinders have equal volume or mass?
4. What caused the cylinders to be different densities?
5. What happens to the density as the volume increases?
6. What happens to the density as the mass increases?
7. Using the table, create a graph of the relationship
between atomic number and density. Is there a relationship? If so
what is it? Is there a periodic trend evident? If so what is it?
8. Using the table, create a graph of the relationship
between atomic mass and density. Is there a relationship? If so
what is it?
9. Using the data from your table, Graph Volume vs
Density. What Type of relationship is this?
10. Using the data from your table: Graph Mass vs Density.
What Type of relationship is this?
11. Would any of these sample float in water? Why or why
not?
12. Given that the density of water is 1.00 g/mL and the
density of ethylene glycol (antifreeze) is 1.114 g/mL, if 100.0
mL of water is combined with 10.0 mL of ethylene glycol, which
liquid would you expect to float on top? Draw a picture to
support your answer.
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