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lOMoARcPSD|19384520

Virtual Lab Manual
Ideal Gas Law: Build your own
temperature scale
Synopsis
Just because Celsius, Fahrenheit and Kelvin defined their own temperature scales and
named them after themselves, it doesn’t mean that you can’t create your own! In the Ideal
Gas Law simulation, you will define the physical concept of temperature and absolute zero
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Define your temperature scale
Your first mission in the Ideal Gas Law simulation will be to define a unique temperature
scale
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You will discover at which temperature water freezes and nitrogen boils
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Formulate the Ideal Gas Law
Imagine how easy it would be to understand the behavior of an ideal gas if the gas molecules
were so big that they could be seen with the naked eye
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Your next
mission is to define the relationship between the pressure, temperature and volume of an
ideal gas sealed in a glass jar
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temperature of boiling water to the temperature of boiling nitrogen
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Are you ready to apply the Ideal Gas Law and everything you learned in gas thermometry in
order to assist the transfer of an organ for a transplant surgery?

Learning Objectives
At the end of this simulation, you will be able to…
● Explain the physical concepts of temperature and absolute zero
● Define the relationship between pressure, volume and temperature in gases using gas
thermometry
● Apply the Ideal Gas Law

Techniques in Lab
● Gas thermometry

Theory
Phase transitions
Phase transitions play an important role in the study of Thermodynamics
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The phase of a given
substance depends on the pressure and temperature
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At ambient pressure and temperature, one would assume that the water in a glass would be
in a liquid form
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If you transfer
the glass of water to the North Pole, most likely the water will transition from the liquid
phase to solid phase as it freezes
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This kinetic energy is divided
among the particles that comprise the substance
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Even
though the velocity, rotation or vibration of a single molecule can be measured, it is
impossible in practice to directly measure the total kinetic energies of all the particles which
make up some macroscopic material like the total amount of gas in a tank
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That's why temperature is typically used to measure or define the average microscopic
kinetic energy of the particles in some material
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Boltzmann constant
The Boltzmann constant, kR, is a physical constant that relates the average kinetic energy of
particles in a gas with the temperature of the gas
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If the temperature is measured in Kelvin and the energy in Joules the constant gets the
following value in SI units:
kR = 1
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The value of the constant has to be adjusted to the temperature scale selected
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Unfortunately, this method is not feasible in the
real world as even tiny objects contain billions of particles
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This can, for example, be the expansion of the length of a column of mercury in a glass
capillary, the bending of a bimetallic strip or a change in the electrical resistivity of a
material or some other physical change
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Temperature scale
Thermometers measure temperature according to well-defined scales of measurement
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Temperature
scales are created by identifying at least two reproducible temperatures
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The table below shows the most common temperature reference points at all three scales:

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Downloaded by Brittany Elizabeth (brittanyelizabeth92@gmail
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15 = T (in K)
T (in oF) = T(in oC) × 9/5 + 32
Absolute zero
Experiments have confirmed the existence of the lowest possible temperature, or the
minimum allowed by quantum mechanics
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At this
point, the average kinetic energy of molecules is zero
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This proportionality is the basis of the constant-volume gas thermometer
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When the proportionalities are combined into a single equation, the constant of
proportionality is independent of the composition of the gas
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A gas at that limit is called an
Ideal Gas; it obeys the Ideal Gas Law, which is also called the equation of state of an Ideal
Gas
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The Ideal Gas Law can be expressed
for Ideal Gases as follows:
pV = NkRT
where p is the absolute pressure of a gas,
V is the volume it occupies,
N is the number of molecules in the gas,
T is its absolute temperature,
and kR is the Boltzmann constant
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Gas Thermometry
The purpose of the Gas Thermometry experiment is to construct a temperature scale and
determine the absolute zero temperature
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In addition, the absolute temperature
scale is determined by extrapolation towards low temperatures
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Generally, gases used in gas thermometry are Ideal Gases
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The left reservoir contains
boiling water and is connected to a variac that controls the power
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The right reservoir is also a
polypropylene tube in a Styrofoam block but this tube contains liquid nitrogen
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The main piece of the apparatus is a dipper which consists of a steel gas vessel attached to
valves and tubing and mounted to a Lexan sheet (to prevent splashing/steam/vapor and to
protect the manometer), a digital manometer and a handle
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The manometer has a digital readout screen
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Note
that like most pressure gauges, the manometer reads in gauge pressure
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Gas thermometry safety rules
Before starting the experiment, there are some key safety issues to aware of:
● Safety glasses must be worn at all times
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The dipper is fragile
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● The power to the hot plates which boil water is controlled by a variac
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● If you or your partner are uncomfortable moving the cylinder/container from each of
the reservoirs, ask the teaching assistant or the technician for help
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Handle liquid nitrogen with respect
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