Calculating Average Kinetic Energy

[Tiffany Chao 2H]

For 4.19, we're supposed to use average kinetic energy = 3/2*RT. I did 3/2(8.314 J/mol.K)(328.85K) and got 4101.09 J/moles. However, the answer key says 4103.2 J/mol. I'm off by a pretty significant amount and I'm not sure what I'm doing wrong since it seems to be a pretty straightforward calculation.

Thanks

[Jared Khoo 1G]

When converting celcius to kelvin, you added 273. For a more accurate conversion, add 273.15 as mentioned on Dr. Lavelle's formula sheet. Also, the textbook probably used R = 8.3145 as the gas constant. This should get the right answer.