The HCl equilibrium bond length is 0.127 nm and the v = 0 to v = 1 transition is observed in the infrared at 2886 cm-1.Compute the vibrational energy of HCl in its lowest state. Compute the classical limit for the stretching of the HCl bond from its equilibrium length in this state. What percent of the equilibrium bond length is this extension

Respuesta :

Answer:

Vibrational Energy Of HCl in the lowest state :

[tex]2.86 \times 10^{-20} J[/tex]

Classical Limit for stretching of HCl bond from its equilibrium length :

[tex]Q_{0} = 0.0109 nm[/tex]

Percent of equilibrium Bond Length :

8.58 %

Explanation:

H-Cl bond Length = 0.127 nm =[tex] 1.27 \times 10^{-10}m[/tex]

Frequency from v = 0 to v = 1 is 2886 [tex]cm^{-1}[/tex]  

[tex]\nu(Hz) = c\times \nu (cm^{-1})[/tex]

[tex]\nu(Hz) = 3 \times 10^{10} \times 2886 [/tex]

[tex]\nu = 8.568 \times 10^{13} Hz[/tex]

Reduced mass

[tex]\mu =\frac{m_{1}m_{2}}{m_{1}+m_{2}}[/tex]

[tex]\mu =\frac{1 \times 35.5}{1+35.5}[/tex]

[tex]\mu =\frac{1 \times 35.5}{36.5}[/tex]

but this has units in amu , to convert it in Kg divide it by

[tex]6.022\times 10^{23}[/tex] and 1000(to convert gram itno Kg)

[tex]\mu = 1.61 \times 10^{-27} Kg[/tex]

Calculation of Force constant :

[tex]\nu =\frac{1}{2\Pi }\sqrt{\frac{k}{\mu }}[/tex]

Here,

[tex]\nu = frequency[/tex]

k = force constant

[tex]\mu = Reduced mass[/tex]

Put the value of frequency , reduced mass and calculate for force constant

[tex]2(3.14)\times 8.658\times 10^{13} = \sqrt{\frac{k}{1.61\times 10^{-27}}}[/tex]

Solve the left hand side and square it. Then multiply it with reduced mass

k = 475.97 N/m

[tex]\omega = 2\Pi \nu[/tex]

[tex]\omega = 2(3.14)(8.568 \times 10^{13} Hz)[/tex]

[tex]\omega = 5.43 \times 10^{14}[/tex]

Calculation of lowest energy

[tex]E_{0} = \frac{h\omega }{2\Pi }[/tex]

h = planck's constant = [tex]6.626 \times 10^{-34}[/tex]

[tex]E_{0} = \frac{(6.626 \times 10^{-34})(5.43 \times 10^{14})}{2\Pi }[/tex]

On solving ,

[tex]E_{0} = 2.86 \times 10^{-20}J[/tex]

Calculation of Stretching of HCl bond:

Use formula :

[tex]\frac{1}{4\Pi }h\omega =\frac{1}{2}kQ_{0}[/tex]

here Q = stretching bond length

Put , k = 475.97 N/m ,[tex]\omega = 5.43 \times 10^{14}[/tex] and solve for Q

[tex]Q_{0}^{2} = 1.204 \times 10^{-22}[/tex]

take square root

[tex]Q_{0} = 1.097 \times 10^{-11}[/tex]

Calculation of Percentage extension:

Percentage[tex] =\frac{Q_{0}}{X_{eq}}\times 100[/tex]

[tex]\frac{1.097 \times 10^{-11}}{1.27 \times 10^{-10}}[/tex]

Percentage = 8.58 %

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