- #1
tahmidbro
- 15
- 1
- Homework Statement
- a) what is the rms speed of four hydrogen molecules with the speeds of 890, 755, 902, 866m/s?
Ans : 855m/s
My problem is part b)
b) at what temperature would these hydrogen molecules be?
( Mass of H atom = 1.67 x 10^(-27) kg )
Now, in 1/2m<c^2> = (3/2)kt, should I use the mass for only 1 hydrogen atom, or mass of 2 hydrogen atoms, or the mass for all 8 atoms in 4 molecules?
- Relevant Equations
- 1/2m<c^2> = 3/2kT
the answer in the solution book is 29K which only comes if I use mass for only one atom. ( They did not show any working )
My attempt:
1/2 x (1.67 x 10^(-27)) x (355)^(2) = 3/2 x 1.38 x 10^(-23) x T
T = 29.48820652 K
The confusion arises when I tried the following question:
Q. Estimate the rms speed of the molecules of air in this room.
The answer given in the solution book :
Estimate of 20 °C (T = 293 K); assume all molecules are dinitrogen, so m = 4.676 × 10^(–26) kg; gives rms = 509m/s.
which is only possible if I use mass of two nitrogen atoms.
Please help :-)
My attempt:
1/2 x (1.67 x 10^(-27)) x (355)^(2) = 3/2 x 1.38 x 10^(-23) x T
T = 29.48820652 K
The confusion arises when I tried the following question:
Q. Estimate the rms speed of the molecules of air in this room.
The answer given in the solution book :
Estimate of 20 °C (T = 293 K); assume all molecules are dinitrogen, so m = 4.676 × 10^(–26) kg; gives rms = 509m/s.
which is only possible if I use mass of two nitrogen atoms.
Please help :-)