The ammonia molecule NH 3 has adipole moment of 4.8e-30 C·m. Ammonia molecules i
ID: 1665775 • Letter: T
Question
The ammonia molecule NH3 has adipole moment of 4.8e-30 C·m. Ammonia molecules in the gasphase are placed in a uniform electric field with magnitude 1590000N/C.a) What is the change in electric potentialenergy when the dipole moment of the molecule changes itsorientation with respect to the electric field from parallel toperpendicular?
b) At what absolute temperature T is theaverage translational kinetic energy 3kT/2 (wherek is the Boltzmann constant) of a molecule equal to thechange in potential energy calculated in part a)? (Above thistemperature, thermal agitation prevents the dipoles from aligningwith the electric field.) a) What is the change in electric potentialenergy when the dipole moment of the molecule changes itsorientation with respect to the electric field from parallel toperpendicular?
b) At what absolute temperature T is theaverage translational kinetic energy 3kT/2 (wherek is the Boltzmann constant) of a molecule equal to thechange in potential energy calculated in part a)? (Above thistemperature, thermal agitation prevents the dipoles from aligningwith the electric field.)
Explanation / Answer
Assume that the dipole is two charge Q and Q that have the distanceof S from each others. Q*S=M=4,8e-30 the potential energy W=2E*S/2*Q=E*M =7,63e-24(J) b) 3kT/2=W so T=2W/3k=0,369(K)