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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:
    PV = NkT , size 12{ ital "PV"= ital "NkT"} {}
    where P size 12{P} {} is pressure, V size 12{V} {} is volume, T size 12{T} {} is temperature, N size 12{N} {} is number of molecules, and k size 12{k} {} is the Boltzmann constant
    k = 1 . 38 × 10 23 J/K . size 12{k=1 "." "38" times "10" rSup { size 8{–"38"} } " J/K"} {}
  • A mole is the number of atoms in a 12-g sample of carbon-12.
  • The number of molecules in a mole is called Avogadro’s number N A size 12{N rSub { size 8{A} } } {} ,
    N A = 6 . 02 × 10 23 mol 1 . size 12{N rSub { size 8{A} } =6 "." "02" times "10" rSup { size 8{"23"} } `"mol" rSup { size 8{ - 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:
    PV = nRT , size 12{ ital "PV"= ital "nRT"} {}
    where n size 12{n} {} is number of moles and R size 12{R} {} is the universal gas constant,
    R = 8 . 31 J/mol K . size 12{R=8 "." "31"`"J/mol" cdot 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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Under what circumstances would you expect a gas to behave significantly differently than predicted by the ideal gas law?

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A constant-volume gas thermometer contains a fixed amount of gas. What property of the gas is measured to indicate its temperature?

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Problems&Exercises

The gauge pressure in your car tires is 2 . 50 × 10 5 N/m 2 size 12{2 "." "50"´"10" rSup { size 8{5} } " N/m" rSup { size 8{2} } } {} at a temperature of 35 . 0 º C size 12{"35" "." 0°C} {} when you drive it onto a ferry boat to Alaska. What is their gauge pressure later, when their temperature has dropped to 40 . 0 º C size 12{ +- "40" "." 0°C} {} ?

1.62 atm

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Convert an absolute pressure of 7 . 00 × 10 5 N/m 2 size 12{7 "." "00" times "10" rSup { size 8{5} } " N/m" rSup { size 8{2} } } {} to gauge pressure in lb/in 2 . size 12{"lb/in" rSup { size 8{2} } "." } {} (This value was stated to be just less than 90 . 0 lb/in 2 size 12{"90" "." "0 lb/in" rSup { size 8{2} } } {} in [link] . Is it?)

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Suppose a gas-filled incandescent light bulb is manufactured so that the gas inside the bulb is at atmospheric pressure when the bulb has a temperature of 20 . 0 º C size 12{"20" "." 0°C} {} . (a) Find the gauge pressure inside such a bulb when it is hot, assuming its average temperature is 60 . 0 º C size 12{"60" "." 0°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 helium-filled 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 10 . 0 º C size 12{"10" "." 0°C} {} and rises to an altitude where its volume is twenty times the original volume and its temperature is 50 . 0 º C size 12{ +- "50" "." 0°C} {} ? (b) What is the gauge pressure? (Assume atmospheric pressure is constant.)

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Confirm that the units of nRT size 12{ ital "nRT"} {} are those of energy for each value of R size 12{R} {} : (a) 8 . 31 J/mol K size 12{8 "." "31"" J/mol" cdot K} {} , (b) 1 . 99 cal/mol K size 12{1 "." "99 cal/mol" cdot K} {} , and (c) 0 . 0821 L atm/mol K size 12{0 "." "0821 L" cdot "atm/mol" cdot K} {} .

(a) nRT = ( mol ) ( J/mol K ) ( K ) = J size 12{ ital "nRT" = \( "mol" \) \( "J/mol" cdot K \) \( K \) =" J"} {}

(b) nRT = ( mol ) ( cal/mol K ) ( K ) = cal size 12{ ital "nRT" = \( "mol" \) \( "cal/mol" cdot K \) \( K \) =" cal"} {}

(c) nRT = ( mol ) ( L atm/mol K ) ( K ) = L atm = ( m 3 ) ( N/m 2 ) = N m = J

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Questions & Answers

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Nyibol Reply
what is microbiologist
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Muhammad
is the branch of biology that deals with the study of microorganisms.
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What is microbiology
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studies of microbes
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Bacteria doesn't produce energy they are dependent upon their substrate in case of lack of nutrients they are able to make spores which helps them to sustain in harsh environments
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But not all bacteria make spores, l mean Eukaryotic cells have Mitochondria which acts as powerhouse for them, since bacteria don't have it, what is the substitution for it?
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they make spores
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the significance of food webs for disease transmission
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food webs brings about an infection as an individual depends on number of diseased foods or carriers dully.
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explain assimilatory nitrate reduction
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Assimilatory nitrate reduction is a process that occurs in some microorganisms, such as bacteria and archaea, in which nitrate (NO3-) is reduced to nitrite (NO2-), and then further reduced to ammonia (NH3).
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This process is called assimilatory nitrate reduction because the nitrogen that is produced is incorporated in the cells of microorganisms where it can be used in the synthesis of amino acids and other nitrogen products
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Examples of thermophilic organisms
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Give Examples of thermophilic organisms
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Prevent foreign microbes to the host
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they provide healthier benefits to their hosts
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They are friends to host only when Host immune system is strong and become enemies when the host immune system is weakened . very bad relationship!
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cell is the smallest unit of life
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cell is the structural and functional unit of life
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is the fundamental units of Life
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There are nothing like emergency disease but there are some common medical emergency which can occur simultaneously like Bleeding,heart attack,Breathing difficulties,severe pain heart stock.Hope you will get my point .Have a nice day ❣️
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Many sites of the body have it Skin Nasal cavity Oral cavity Gastro intestinal tract
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part of a tissue or an organ being wounded or bruised.
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Binomial nomenclature
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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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