Enter formulas and temperatures in the boxes below: 1 = slowest, 4 = fastest

Question

Arrange the following molecules in order of increasing average molecular speed.

Ne at 390K, Ar at 315K, NH₃ at 390K, NH₃ at 440K

Answer 1

RMS = √3RT/M where R = 8.314 kgm3/s2; T = kelvin; M = molar mass in kg

Ne @ 390K: RMS = √(8.314)(390)/0.02 = 403 m/s

Ar @ 315K: RMS = √(8.314)(315)/0.0399 = 256 m/s

NH₃ @ 390K: RMS = √(8.314)(390)/0.017 = 437 m/s

NH₃ @ 440K: RMS = √(8.314)(440)/0.017 = 464 m/s

1 = slowest and 4 = fastest we have...

1 = Ar @ 315K

2 = Ne @ 390K

3 = NH₃ @ 390K

4 = NH₃ @ 440K

Hopefully the calculations are correct.