Identifying Three Unknown Metals Through Calculation of Density
Abstract:
Metals and other substances can be identified several ways. The easiest and most
efficient is via density. Density can be determined by dividing how tightly an object’s
atoms are (mass) by how much space it occupies (volume). All substances contain two
properties: physical and chemical. These properties also help identifying an object or
substance. The hypothesis for the experiment was that the cylinders were iron, copper,
and aluminum. After the mass and volume were calculated, the densities were incorrectly
identified the cylinders as scandium, niobium, and bismuth; in fact my hypothesis was
correct in that the cylinders were iron, copper, and aluminum, although the data did not
support this fact.
Introduction:
Metals, by definition, are “shiny solids that are room temperature, with
characteristic high melting points and densities.” Metals vary in shape, size, and through
many other properties. These properties include a shiny metallic appearance, high
melting points and densities, large atomic radii, and low ionization energies and electro
negativities (Helmenstine, 2009). Often metals are solids at room temperature, except for
mercury (Wysession, 2004). Many metals are ductile, meaning that they can be drawn
into thin wires. An example of a metal that we see ductile frequently is copper, which
runs through many electric wires. Malleability is a metals ability to deform under
pressure. (Byrne, 2009). A very common malleable metal is aluminum, which is pressed
to make aluminum foil which most use to preserve food.
Metals are commonly classified by most people according to their luster, or the
shine that they give off when exposed to light. Many metals including gold, silver,
platinum, and rhodium are very shiny. Some metals, just like some minerals, are
classified as precious. These metals are somewhat rare and are highly valuable. Some
renowned ones are gold, silver, germanium, platinum, with the highest vale belonging to
rhodium, a whitish-silver metal that is found in a Catalytic Converter in most cars. Metals
are often identified by their densities. Density is the ratio of an object’s mass to its
volume.
Mass by definition is the amount of matter in an object; matter makes up
everything and is found everywhere. Mass is commonly misconceived; most people
assume that mass is how much an object weighs. This is spurious. In fact, they are
similar, but very different. Mass is how much matter is in an object, disregarding gravity.
Mass is often calculated by a triple or quadruple beam balance and is measured in a unit
known as grams (g). Weight is how much an object weighs, with regard to the
gravitational pull on an object. The mass of an object stays the same everywhere: on
Earth, in space, on other planets; weight changes, depending on the object’s gravitational
pull (Qualitative Reasoning Group)
Volume is the amount of space an object occupies. Volume can be calculated
easily through two different methods. One method is through mathematic formulas.
Formulas are used better for objects with defined geometric shapes, such as a cube,
rectangular prism, cylinder or sphere. The SI unit for volume is Liters (L) for liquids and
gases, and Meters cubed (m3). Some formulas are:
Volume of a Rectangular Prism = l x w x h
Volume of Cylinder = πr2 x h
Volume of a Cube = s3
Volume of a Sphere = 1⅓ x πr2
The other way of calculating volume is through displacement. Displacement is
using a graduated cylinder, beaker, et cetera filled with water to find an objects volume.
To calculate volume through displacement, one must first measure the original amount of
water in the beaker from its meniscus, then drop the object in, and read the new
measurement. Subtract them, and your difference is the objects volume.
Density is very important to an object’s identity. When trying to determine
what an object is, the density will be very helpful. The density of an object, according to
Mr. Boylan, “is how tightly packed the atoms of an object are, in relation to how much
space it occupies”. Density plays a large roll when it comes to identification. For
example, you find a small piece of a white solid. You calculate its mass and volume and
find its density. You look up the mass and volume on your computer, but many different
items come up. When you look up the density of it, it shows up that it is chalk. The small
piece of chalk had the same density of the full piece of chalk. Why? Density doesn’t
change, although when broken, the mass and volume do change. Density will always be
the same. Therefore you can identify an item best by calculating its density.
Density itself doesn’t have a particular SI unit. Rather it is a formula consisting of
two different SI units, either g/cm3 or g/L
DENSITY = MASS / VOLUME
Example: Mass = 40g , Volume = 10cm3
40/10= 4 g/cm3
All objects have properties; science states that objects have two sets of properties:
physical and chemical. Physical properties include all things that one can observe about
the object without changing its identity. These include such properties as color, texture,
elasticity, density, viscosity, volume, mass, sound, conductivity, etc. The other set of
properties are chemical. Chemical properties are properties that can only be observed by
changing the identity of the object or substance. These include: flammability, acidity,
basicity, combustion, toxicity, and rustability (Wysession, 2004). These categories can be
further diminished through extensive and intensive categories.
“Intensive properties of matter depend only upon the identity of the substance.
This is to say that any size sample of a particular substance will have these properties.
Extensive properties depend upon a particular sample of a particular substance” (Boylan,
2009). Scandium, a metal, was discovered in 1879, named for Scandinavia. It burns
quickly when ignited, and is used to make parts for fighter jets (Barbalace, 2007).
Bismuth, another metal, was discovered in ancient times. It is used as an alloy for several
purposes, including pharmaceuticals (Barbalace, 2007). It has the lowest thermal
conduction except for mercury. Formerly known as Columbium, Niobium is used for jets,
nuclear reactors, missiles, etc. (Barbalace, 2007). Copper is a reddish-brown metal which
is used for many purposes, including window paneling, coining, pot-making, and jewelry.
Aluminum is a very whitish-silver metal which is very light. Its most well known purpose
is to preserve and protect food (aluminum foil). Iron is a very dark metal which is very
heavy and sturdy. It is used for building purposes mainly.
The purpose of the experiment was to identify the three given cylinders. By
setting up the following experiment, hopefully our question will be answered.
The hypothesis for the experiment was based on the cylinder’s color, smell, and weight.
The rusty-looking one (Cylinder A) seemed to be iron because iron normally rusts and it
just looked what iron normally looks like. The silvery one (Cylinder B) appeared to be
aluminum, due to its lightlessness, like in aluminum foil, and due to its smell. The
coppery one (Cylinder C) was thought to be copper because it smelled like pennies and
its hue and shine resembled that of copper. The hypothesis is that Cylinder A would be
iron, Cylinder B would be aluminum, and that Cylinder C will be copper.
Materials and Methods:
The following materials were gathered and used for the experiment:

(1) Quadruple Beam Balance

(1) Ruler

(3) Unknown Metallic Cylinders

(1) 50 Ml Graduated Cylinder

(1) Copy of Table S from the Chemistry Reference Tables
First, all of the materials were gathered and positioned on the lab table for usage.
The cylinders were examined and were categorized into two columns: extensive and
intensive. The numerous physical properties were recorded into these columns. Observed
extensive properties of the group were color, mass, weight, luster, density and buoyancy.
Observed intensive properties of the bunch were height, radius, width, and volume. One
at a time, each cylinder was placed on the quadruple beam balance. Each cylinder’s mass
was then calculated. Next, a 50mL graduated cylinder was filled with water to the 25mL
mark. One at a time, the cylinders were dropped in at an angle. The difference between
the original meniscus and the new meniscus was recorded. Then the cylinders were
measured. Using the formula, πr2 x h, the volumes were calculated mathematically. Tables
were set up to record the data.
Results:
Table 1: Metal References
Metal
A
B
C
Color
Rusty-Looking
Silvery-Looking
Copper-Looking
Table 2: Mass and Volume of Various Unknown Metals
Metal
Mass (g)
Volume (cm3) [via Displacement]
Volume(cm3) [via Mathematic Formula]
A
49.95
6
5.95
B
17.9
6
5.95
C
57.71
6
5.95
Table 3: Density of Unknown Identities
Density (g/cm3)
8.32
2.9
9.62
Metal
A
B
C
Table 4: Contingent Identities of Unknown Metals via Table S
Metal
Identity
Density (g/cm3)
Table S Value (g/cm3)
A
Niobium
8.32
8.57
B
Scandium
2.9
2.989
C
Bismuth
9.62
9.747
Discussion:
The data provided has led to a clear, apparent conclusion based on the research.
The research and experiment have led to a clear conclusion. The cylinders were
composed of scandium, bismuth, and niobium. Later, the data was deemed incorrect. The
experiment must have had a problem. The greatest probable reason was human error.
When the measurements were recorded, human error must have not accurately
determined the right measurements. Another possibility is that when referring to Table S,
the comparer decided to make a choice when the measurement was between two or more
possibilities on Table S. In fact, the cylinders were iron, aluminum, and copper; therefore
my original hypothesis was correct, although the data did not support it.
Literature Cited
Barbalace, Kenneth. “Element Bismuth: Bi”: J.K. Barbalace Inc. Page Last Updated:
2/22/07. Page Visited on October 4th, 2009.
http://environmentalchemistry.com/yogi/periodic/Bi.html
Barbalace, Kenneth. “Element Niobium: Nb”: J.K. Barbalace Inc. Page Last Updated:
2/22/07. Page Visited on October 4th, 2009.
http://environmentalchemistry.com/yogi/periodic/Nb.html
Barbalace, Kenneth. “Element Scandium: Sc”: J.K. Barbalace Inc. Page Last Updated:
2/22/07. Page Visited on October 4th, 2009.
http://environmentalchemistry.com/yogi/periodic/Sc.html
Boylan, James. “Lab #2: Identification of Three Metals by Density Determination”. New
York, NY. September 24th, 2009.
Byrne, Oliver. “Malleability and Ductility of Alloys”: Stasosphere. Excerpt from novel
“The Practical Metal-Worker's Assistant”, published in 1874. Last Updated: 2/21/09.
Page Visited on October 2nd, 2009. http://chestofbooks.com/crafts/metal/Metal-WorkerAssistant/Malleability-And-Ductility-Of-Alloys.html
Helmenstine, Anne Marie. “Metals: Properties of Element Groups”. The New York
Times Company. Page Last Updated: unknown (between 2001- 2009). Page Visited on
October 2nd, 2009. http://chemistry.about.com/od/elementgroups/a/metals.htm
Quantitive Reasoning Group. “Space Environment: What is Mass?”. Northwestern
University. Page Last Updated: unknown. Page Visited on October 2nd, 2009.
http://www.qrg.northwestern.edu/projects/vss/docs/space-environment/2-what-ismass.html
Wysession, Michael/ Frank, David/ Yancopoulos, Sophia. “Physical Science: Concepts in
Action”. Upper Saddle River, New Jersey: Pearson Prentice Hall Publishers. 2004.