Constants Part A The ammonia molecule (NHs) has a dipole moment of 5.0 x 10-30C

Question

Constants Part A The ammonia molecule (NHs) has a dipole moment of 5.0 x 10-30C . m. Ammonia molecules in the gas phase are placed in a uniform electric field B with magnitude 1.6x106 N/C What is the change in electric potential energy when the dipole moment of a molecule changes its orientation with respect to E from parallel to perpendicular? Express your answer using two significant figures. Submit Part B At what absolute temperature T" is the average translational kinetic energykT of a molecule equal to the change in potential energy calculated in part (a)? (Note: Above this temperature, thermal agitation prevents the dipoles from aligning with the electric field.) Express your answer using two significant figures. Submit Request Answer

Explanation / Answer

Given

ammonia molecule with dipole moment is p = 5*10^-30 C.m

and the electric field E = 1.6*10^6 N/C

Part A

we know that the potential energy is u = -p.E , change in potential energy is  

dU = -p*E ( cos theta2- cos theta1)

dU = -5*10^-30*1.6*10^6(cos90-cos0) J

dU = 8*10^-24 J

Part B

Average translational kinetic energy E = 3/2*k*T

8*10^-24 = (3/2)1.38064852*10^-23*T

solving for T , T = 0.3862 k

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