How Do You Calculate the Kinetic Energy of CO, CO2, and SO3 at 276 K?

[SpottedGreen]

Homework Statement

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

Homework Equations

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

The Attempt at a Solution

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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
4.65x10^-23g
4.65x10^-26kg

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

 

[Ygggdrasil]

KE = (3/2) RT

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.