Sydni Jordan- Warren Mott High School

Kyla Semones – Cousino High School

Purpose

• To determine whether or not a metal rod is composed of Molybdenum based percent error and the intensive properties of specific heat and linear thermal expansion.

Terms To Know

• Specific Heat – The amount of heat that it takes to increase

the temperature of a metal by one degree Celsius.

• Units: J / g * ºC

Terms to Know

• Linear Thermal Expansion– A metal's change in length when it

experiences a change in temperature• Units: ºC-1

Terms to Know

• Kinetic Molecular Theory– States that atoms are constantly in motion

and when heat is applied to a system, the speed of the atoms’ motion increases.

Terms to Know

• First Law of Thermodynamics– Energy is neither created nor destroyed.

• Isolated System– A container that does not allow the matter or

heat inside to escape• Ex: Calorimeters

Terms to Know

• Intensive Property– A property that is unique to a specific element

and does not depend on the sample size

Terms to Know

Molybdenum Background

• Discovered by Carl Welhelm Scheele in 1778.

Molybdenum Background

Characteristics•Mo•Density: 10.22 g/cm3 •Atomic Number: 42•Atomic Mass: 95.94 amu•Hard and silvery

• Electron Configuration– [Kr] 4d5 5s1

Molybdenum Background

• Most common use commonly used in Steel alloys– stronger steel– higher heat tolerance– higher resistance to corrosion

Molybdenum Background

• Isolation

• 2MoS2 + 7O2 2MoO3 + 4SO2

• MoS2 + 6MoO3 7MoO2 + 2SO2

• 2MoO2 + O2 2MoO3

Molybdenum Background

• Specific Heat– 0.25 J/g x ºC

• Linear Thermal Expansion Coefficient– 4.8 x 10-6

Molybdenum Background

Problem

• The researchers will use linear thermal expansion and specific heat equations along with percent error to correctly determine whether or not the unknown metal rod is made of Molybdenum.

Hypothesis

• When the linear thermal expansion coefficient, specific heat, and the average percent error for the trials are calculated, the researchers will conclude that the unknown metal rod will not be composed of Molybdenum.

Tests Used

• Specific Heat Test

• Linear Thermal Expansion Coefficient Test

Test I. Specific Heat

Specific Heat

Equation used:

Calorimeter Building

• To conduct the specific heat tests, three calorimeters were built.

Specific Heat Materials

Specific Heat Test

• Mass of the rod was taken• Rod was placed in boiling water for 3

minutes• Rod was placed into a calorimeter with

water• The equilibrium temperature was found• Specific Heat was calculated

Molybdenum Specific Heat Results

• Molybdenum Averages– Specific Heat Rods: 0.236– Percent Error: 16.320

• Observations– Rod never boiled over three minutes and five

seconds– Window opened during and after trial 8

Unknown Specific Heat Results

• Unknown Metal Averages– Specific Heat: 0.277– Percent Error: 84.098

• Observations– Rods never boiled over thirty seconds– The window was opened during the testing

for all of the trials

Specific Heat Results

Molybdenum

Unknown

Two-Sample t-Test

• Assumptions– SRSs– independent samples– 15 of more trials– unknown standard deviation of population

Two-Sample t-Test

Two-Sample T Test Results

• T-value = -1.315

• P-value = 0.204

• Failed to reject null hypothesis

– 0.204 > alpha value 0.1

Test II. Linear Thermal Expansion Coefficient

Linear Thermal Expansion

Linear Thermal Expansion Materials

Linear Thermal Expansion Video

Molybdenum Linear Thermal Expansion Results

• Averages of Molybdenum– Alpha coefficient: 2.806 x 10-6

– Percent Error: 41.543

• Observations– Window opened for trials 5 through 12– Never boiled for over three minutes and ten

seconds

Unknown Linear Thermal Expansion Results

• Averages of Unknown Metal– Alpha coefficient: 5.197 x 10-6

– Percent Error: 8.988

• Observations– Never boiled for more than three minutes and

ten seconds– Window closed through entire test

Linear Thermal Expansion Results

Molybdenum

Unknown

Two-Sample t-Test

• Assumptions– SRSs– independent samples– 15 of more trials– unknown standard deviation of population

Two-Sample t-Test

Two-Sample t-Test Results

• T-Value = -9.837

• P-value = 7.633 x 10-10

• Rejected null hypothesis

– 7.633 x 10-8 < alpha level 0.1

What have we concluded?

• Results of the t- tests may be deemed inconclusive– One assumption was not met– The mean that was calculated from the

Molybdenum rods was not close to the actual alpha coefficient for Molybdenum, 4.8 x 10-6.

Accept or Reject?

• Hypothesis

• Accepted Rejected

Why reject?

• Percent Error

• Linear Thermal Expansion– P-value: 7.633 x 10-10

Flaws

• Metal transfer• Metal temperature assumptions

Limitations

• Opening/Closing of windows• Calorimeters

Real World Applications

• Mining• Plumbing• Architecture

Further Research

• Melting Point Test• Boiling Point Test• Density Test

Acknowledgements

• Jeff Wainz• Mrs. Hilliard• Mr. Supal• Mrs. Dewey

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Questions?