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: 2 Volume of a Rectangular Prism = l x w x h Volume of Cylinder = πr x h

3 2 Volume of a Cube = s Volume of a Sphere = 1⅓ x πr

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

2 measured. Using the formula, πr x h, the volumes were calculated mathematically. Tables

were set up to record the data.

Results: Table 1: Metal References

Metal Color A Rusty-Looking B Silvery-Looking C Copper-Looking

Table 2: Mass and Volume of Various Unknown Metals

Meta l 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

Metal Density (g/cm3) A 8.32 B 2.9 C 9.62

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

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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-Worker- Assistant/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-is- mass.html

Wysession, Michael/ Frank, David/ Yancopoulos, Sophia. “Physical Science: Concepts in Action”. Upper Saddle River, New Jersey: Pearson Prentice Hall Publishers. 2004.