



Section summary
 The ideal gas law relates the pressure and volume of a gas to the number of gas molecules and the temperature of the gas.
 The ideal gas law can be written in terms of the number of molecules of gas:
$\text{PV}=\text{NkT},$
where
$P$ is pressure,
$V$ is volume,
$T$ is temperature,
$N$ is number of molecules, and
$k$ is the Boltzmann constant
$k=1\text{.}\text{38}\times {\text{10}}^{\u2013\text{23}}\phantom{\rule{0.25em}{0ex}}\text{J/K}.$
 A mole is the number of atoms in a 12g sample of carbon12.
 The number of molecules in a mole is called Avogadro’s number
${N}_{\text{A}}$ ,
${N}_{\text{A}}=6\text{.}\text{02}\times {\text{10}}^{\text{23}}\phantom{\rule{0.25em}{0ex}}{\text{mol}}^{1}.$
 A mole of any substance has a mass in grams equal to its molecular weight, which can be determined from the periodic table of elements.
 The ideal gas law can also be written and solved in terms of the number of moles of gas:
$\text{PV}=\text{nRT},$
where
$n$ is number of moles and
$R$ is the universal gas constant,
$R=8\text{.}\text{31}\phantom{\rule{0.25em}{0ex}}\text{J/mol}\cdot \text{K}.$
 The ideal gas law is generally valid at temperatures well above the boiling temperature.
Conceptual questions
Find out the human population of Earth. Is there a mole of people inhabiting Earth? If the average mass of a person is 60 kg, calculate the mass of a mole of people. How does the mass of a mole of people compare with the mass of Earth?
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Problems&Exercises
The gauge pressure in your car tires is
$2\text{.}\text{50}\times {\text{10}}^{5}\phantom{\rule{0.25em}{0ex}}{\text{N/m}}^{2}$ at a temperature of
$\text{35}\text{.}0\text{\xba}\text{C}$ when you drive it onto a ferry boat to Alaska. What is their gauge pressure later, when their temperature has dropped to
$\u2013\text{40}\text{.}0\text{\xba}\text{C}$ ?
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Convert an absolute pressure of
$7\text{.}\text{00}\times {\text{10}}^{5}\phantom{\rule{0.25em}{0ex}}{\text{N/m}}^{2}$ to gauge pressure in
${\text{lb/in}}^{2}\text{.}$ (This value was stated to be just less than
$\text{90}\text{.}{\text{0 lb/in}}^{2}$ in
[link] . Is it?)
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Suppose a gasfilled incandescent light bulb is manufactured so that the gas inside the bulb is at atmospheric pressure when the bulb has a temperature of
$\text{20}\text{.}0\text{\xba}\text{C}$ . (a) Find the gauge pressure inside such a bulb when it is hot, assuming its average temperature is
$\text{60}\text{.}0\text{\xba}\text{C}$ (an approximation) and neglecting any change in volume due to thermal expansion or gas leaks. (b) The actual final pressure for the light bulb will be less than calculated in part (a) because the glass bulb will expand. What will the actual final pressure be, taking this into account? Is this a negligible difference?
(a) 0.136 atm
(b) 0.135 atm. The difference between this value and the value from part (a) is negligible.
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Large heliumfilled balloons are used to lift scientific equipment to high altitudes. (a) What is the pressure inside such a balloon if it starts out at sea level with a temperature of
$\text{10}\text{.}0\text{\xba}\text{C}$ and rises to an altitude where its volume is twenty times the original volume and its temperature is
$\u2013\text{50}\text{.}0\text{\xba}\text{C}$ ? (b) What is the gauge pressure? (Assume atmospheric pressure is constant.)
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Confirm that the units of
$\text{nRT}$ are those of energy for each value of
$R$ : (a)
$8\text{.}\text{31}\phantom{\rule{0.25em}{0ex}}\text{J/mol}\cdot \text{K}$ , (b)
$1\text{.}\text{99 cal/mol}\cdot \text{K}$ , and (c)
$0\text{.}\text{0821 L}\cdot \text{atm/mol}\cdot \text{K}$ .
(a)
$\text{nRT}=(\text{mol})(\text{J/mol}\cdot \text{K})(\text{K})=\text{J}$
(b)
$\text{nRT}=(\text{mol})(\text{cal/mol}\cdot \text{K})(\text{K})=\text{cal}$
(c)
$\begin{array}{lll}\text{nRT}& =& (\text{mol})(\text{L}\cdot \text{atm/mol}\cdot \text{K})(\text{K})\\ & =& \text{L}\cdot \text{atm}=({\text{m}}^{3})({\text{N/m}}^{2})\\ & =& \text{N}\cdot \text{m}=\text{J}\end{array}$
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Questions & Answers
how lesers can transmit information
griffts bridge derivative
please explain; when a glass rod is rubbed with silk, it becomes positive and the silk becomes negative yet both attracts dust. does dust have third types of charge that is attracted to both positive and negative
what is a conductor
Timothy
no....I said below me ...... nothing below .....ok?
dust particles contains both positive and negative charge particles
Mbutene
corona charge can verify
Stephen
when pressure increases the temperature remain what?
CT scanners do not detect details smaller than about 0.5 mm. Is this limitation due to the wavelength of x rays? Explain.
The Critical Angle Derivation
So the critical angle is defined as the angle of incidence that provides an angle of refraction of 90degrees. Make particular note that the critical angle is an angle of incidence value. For the waterair boundary, the critical angle is 48.6degrees.
dude.....next time Google it
pls who can give the definition of relative density?
Temiloluwa
the ratio of the density of a substance to the density of a standard, usually water for a liquid or solid, and air for a gas.
Chidalu
it is the product of mass ×velocity of an object
Chidalu
how do I
highlight a sentence]p? I select the sentence but get options like copy or web search but no highlight. tks. src
then you can edit your work anyway you want
Wat is the relationship between Instataneous velocity
Instantaneous velocity is defined as the rate of change of position for a time interval which is almost equal to zero
Astronomy
The potential in a region between x= 0 and x = 6.00 m
lis V= a+ bx, where a = 10.0 V and b = 7.00 V/m.
Determine (a) the potential atx=0, 3.00 m, and 6.00 m
and (b) the magnitude and direction of the electric
ficld at x =0, 3.00 m, and 6.00 m.
energy is when you finally get up of your lazy azz and do some real work 😁
what are the basic of physics
faith
base itself is physics
Vishlawath
tree physical properties of heat
tree is a type of organism that grows very tall and have a wood trunk and branches with leaves... how is that related to heat? what did you smoke man?
algum profe sabe .. Progressivo ou Retrógrado e Acelerado ou Retardado
V= +23 m/s V= +5 m/s
0__> 0__>
__________________________>
T= 0 T=6s
Claudia
Source:
OpenStax, College physics. OpenStax CNX. Jul 27, 2015 Download for free at http://legacy.cnx.org/content/col11406/1.9
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