تم الحل ✓
categoryكيمياء
schoolبكالوريوس
event_available2026-07-13
السؤال
Transcribed Image Text:
Consider the H2 molecule:
a. The force constant of H2 is k = 510 N/m. Calculate the fundamental vibrational frequency
(in units of cm-¹), the zero-point energy (i.e. energy of the ground vibrational state) in
Joules, and the energies of the first two excited vibrational states, assuming that the H2
molecules behaves as a simple harmonic oscillator.
b. When an IR spectrum of H2 is measured experimentally, no actual absorption of IR light is
observed at the vibrational frequency calculated above (or at any other frequency for that
matter). Why?
c. An analytical expression that provides a good approximation to a potential energy curve
for a real diatomic molecule as a function of the internuclear separation, x, is a so-called
Morse potential given by:
V(x) = D(1-e-B(x-R₂))2
where Re is the equilibrium bond distance, and parameters D and ẞ represent the
dissociation energy of the molecule and the measure of curvature of V(x) at its minimum.
Given that for H₂ we have k = 510 N/m, R = 74.1 pm, D = 7.61×10-19 J and ẞ = 0.0193
pm-¹, on the same graph:
i. plot the harmonic oscillator potential V(x) = 1½ k(x - R₂)² for x between 0 and 400
pm
ii. plot the Morse potential energy curve (expression above) for x between 0 and 400
pm
iii. indicate as horizontal lines the energies of the ground vibrational state and the first
two excited vibrational states calculated in part (a) in the harmonic oscillator
approximation
d. The solution of the Schrödinger equation for the Morse potential yields the following
expression for the vibrational energy levels (in units of cm-1) of a diatomic molecule:
En (n+1/2) (n + 1/2)²
where n is the vibrational quantum number, v is the fundamental vibrational frequency (in
cm-1) that you calculated in part a), and is the anharmonicity constant given by:
x=hcv/4D. Assuming that the H2 molecule is accurately described by a Morse potential
energy curve, calculate what is the highest vibrational energy level that the molecule can
occupy without dissociating into two H atoms.
check_circle الجواب — حل مفصل خطوة بخطوة
hourglass_top
🔒
الحل الكامل متاح للمشتركين
اشترك في أرشيف الأسئلة لعرض هذا الحل وآلاف الحلول المفصلة خطوة بخطوة من معلمين معتمدين.