physics Root Mean Square Speed

At 2000oC
Gas constant R = 8.314 J mol-1 K-1
Absolute temperature T = 2000 + 273 = 2273K
Molar mass M = 4 g mol-1

Root mean square speed
= √[3RT/M]
= √[3(8.314)(2273)/(4)]
= 119.1 m s-1


At 27oC
Gas constant R = 8.314 J mol-1 K-1
Absolute temperature T = 27 + 273 = 300 K
Molar mass M = 4 g mol-1

Root mean square speed
= √[3RT/M]
= √[3(8.314)(300)/(4)]
= 43.3 m s-1
=

2009-05-09 07:08:04 補充：
Sorry, I have made a mistake in molar mass.

Molar mass is in g/mol in most cases in Chemistry, but should be in kg/mol in calculation of root mean square speed. The amended answer is as follows:

Root mean square speed
= √[3RT/M]
= √[3(8.314)(300)/(4/1000)]
= 1370 m/s

我猜M應該 = 0.004 instead of 4
因為physics的單位應該用SI unit... 即應是0.004 kgmol^-1