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Homework Help: Average Kinetic Energy of Gas

  1. Jun 24, 2016 #1
    1. The problem statement, all variables and given/known data

    Calculate the kinetic energy of CO, CO2, and SO3 at 276 K .

    2. Relevant equations

    KE = (3/2) RT
    KE= (1/2)(mass)(velocity)^2

    3. The attempt at a solution

    For CO:
    First attempt: KE=(3/2)(RT)=(3/2)(8.314 J/mol-K)(276K) = 3441.996 -- So that's wrong
    Second attempt:
    Relative Molecular Mass of CO= 28
    6.02x10^23 molecules of CO= 28g
    1 molecule of CO= 28/6.02x10^23

    Kinetic energy of CO= 1/2(4.65x10^-26)(490^2)
    = 5.58x10^-21 J -- according to mastering this is also wrong

    Thank You
  2. jcsd
  3. Jun 24, 2016 #2


    User Avatar
    Science Advisor
    2017 Award

    I believe this equation applies only to monatomic ideal gases. For molecules, such as CO, CO2, and SO3, you need to calculate the number of degrees of freedom for each of these molecules.
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