Anonymous asked in Science & MathematicsPhysics · 1 decade ago

Very hard physics problem....HELP!?

Find the total kinetic energy content of 1.31 moles of an ideal gas at temperature 435 K.

Data: Avogadro's number = 6.023·1023

I am supposed to use the equation...KE=(3/2)*k*T but I have no clue how to apply it.

6 Answers

  • 1 decade ago
    Best Answer

    For any ideal gas, the KE of each molecule is...

    3/2(kb)T = KE of each molecule,

    where kb = Boltzmann's constant = 1.381 x 10^-23 J/K

    T = absolute temperature = 435K (given)

    3/2(1.381 x 10^-23)(435) = KE of each molecule

    9.01 x 10^-21 J = KE of each molecule

    NA = Avogadro's number = 6.023 x 10^23 particles/kmoles

    No. of molecules = 1.31 kmoles x 6.023 x 10^23/kmoles

    No. of molecules = 7.89 x 10^23

    Total KE = KE of each molecule x No. of molecules

    Total KE = (9.01 x 10^-21)(7.89 x 10^23)

    Total KE = 7108.89 Joules or 7.1kJ

    ANSWER: 7.1kJ

    teddy boy

  • 1 decade ago

    K is the Boltzmann Constant, which is the universal gas constant R = 8.314 divided by Avagadro's number. Therefore k has a value of 1.380*10^-23 J K ^-1

    Ek would then be 1.5* 1.380*10^-23* 435 J

    = 9.00 * 10^-21J per molecule.

    For 1 mol, multiply by Avagadro's number. But this is just going around in circles because above we divided by Avagadro's number to get the Boltzmann constant.

    It is there fore much simpler to say that the kinetic energy of 1 mol ideal gas is given by the equation:

    Ek = 3/2 RT where R is the universal gas constant and T is temperature in K . For 1.31 mol multiply again by 1.31.

    I leave it to you to do the arithmetic.

  • 1 decade ago

    k = 1.381 x 10^-23 J/K

    Look under "Cruft".

    KE is the average kinetic energy of a molecule at the temperature K.

    Multiply out the temperature, the k, the number of molecules in tn a mole and the number of moles to get total KE.

    P.S. I get 7110 Joules (3 sig figs) It is convenient that the 10^23 and the 10^-23 cancel out.

  • Anonymous
    1 decade ago

    i cant give you the answer but it looks more like chemistry if that would help you find out more

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  • Anonymous
    1 decade ago

    2 points! wooooo lol

  • 1 decade ago

    3.67^97 is the answer, well, using your formula (i'm pretty sure). =)

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