



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 many subject is in physics
the write question should be " How many Topics are in O Level Physics, or other branches of physics.
effiom
how many topic are in physics
Praise
yh I need someone to explain something im tryna solve . I'll send the question if u down for it
a ripple tank experiment a vibrating plane is used to generate wrinkles in the water .if the distance between two successive point is 3.5cm and the wave travel a distance of 31.5cm find the frequency of the vibration
Tamdy
the range of objects and phenomena studied in physics is
straight line motion is called linear motion
linear motion is a motion in a line, be it in a straight line or in a non straight line. It is the rate of change of distance.
Saeedul
your are wrong Saeedul
Richard
Linear motion is a onedimensional motion along a straight line, and can therefore be described mathematically using only one spatial dimension
Jason
is a onedimensional motion along a straight line, and can therefore be described mathematically using only one spatial dimensions.
Praise
what is a classical electrodynamics?
Marga
dynamic is the force that stimulates change or progress within the system or process
Oze
what is the formula to calculate wavelength of the incident light
if a spring is is stiffness of 950nm1 what work will be done in extending the spring by 60mmp
State the forms of energy
Word : Mechanical wave
Definition :
The waves, which need a material medium for their propagation, e.g., Sound waves. \n\nOther Definition: The waves, which need a material medium for their propagation, are called mechanical waves. Mechanical waves are also called elastic waves. Sound waves, water waves are examples of mechanical waves.t Definition: wave consisting of periodic motion of matter; e.g. sound wave or water wave as opposed to electromagnetic wave.h
a wave which require material medium for its propagation
syed
The S.I unit for power is what?
it can be in kilowatt, megawatt and so
Femi
SI.unit of power is.watt=j/c.but kw.and Mw are bigger.umots
syed
study of matter and its nature
Akinpelu
The word physics comes from a Greek word Physicos which means Nature.The Knowledge of Nature. It is branch of science which deals with the matter and energy and interaction between them.
Uniform
why in circular motion, a tangential acceleration can change the magnitude of the velocity but not its direction
because it is balanced by the inward acceleration otherwise known as centripetal acceleration
MUSTAPHA
Tramsmission of energy through a media
Mateo
is the disturbance that carry materials as propagation from one medium to another
Akinpelu
find the triple product of (A*B).C given that A =i + 4j, B=2i  3j and C = i + k
Difference between north seeking pole and south seeking pole
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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