What new temperature will a gas have if its speed has to become doubled compared to 127^@ "C"127C?

1 Answer
Jul 29, 2017

Whatever quadruple the temperature in "K"K is. Would this apply to RMS speed and average speed as well? Why?


The most probable speed is given by

v_(mp) = sqrt((2k_BT)/m)vmp=2kBTm,

where:

  • k_BkB is the Boltzmann constant in "J/K"J/K.
  • TT is temperature in "K"K.
  • mm is the single-particle mass in "kg"kg.

If you want to double the most probable speed as that at 127^@ "C"127C, or "400.15 K"400.15 K, you want...

v_(mp)' = 2v_(mp) = 2sqrt((2k_BT)/m)

= sqrt((2k_B cdot color(red)(4T))/m)

i.e. the temperature in "K" should quadruple to color(blue)("1600.60 K").


Or with any other speed that follows from the Maxwell-Boltzmann distribution, i.e. any other speed that has the relationship:

v prop sqrtT

We have...

2v prop sqrt(4T)

=> temperature in "K" must have quadrupled.