The bright yellow light emitted by a sodium vapor lamp consists of two emission lines at \(589.0\) and \(589.6 \mathrm{~nm}\). What are the frequency and the energy of a photon of light at each of these wavelengths? What are the energies in \(\mathrm{kJ} / \mathrm{mol}\) ?

Short Answer

Expert verified
The frequencies and energies of the two emission lines at wavelengths \( 589.0 \mathrm{~nm} \) and \( 589.6 \mathrm{~nm} \) can be found using the formulas \( \nu = \frac{c}{\lambda} \) and \( E = h\cdot\nu \). After calculating the frequencies and energies, the energies can be converted to kJ/mol using the conversion factors \( 1 \mathrm{~J} = 1\times10^{-3} \mathrm{~kJ} \) and \( 1 \mathrm{~mol} = 6.022\times10^{23} \mathrm{~photons} \). The final results are: For \( 589.0 \mathrm{~nm} \) wavelength: frequency \( \nu_1 \), energy \( E_1 \), and energy in kJ/mol \( E_{1, kJ/mol} \). For \( 589.6 \mathrm{~nm} \) wavelength: frequency \( \nu_2 \), energy \( E_2 \), and energy in kJ/mol \( E_{2, kJ/mol} \).

Step by step solution

01

Calculate the frequency for \( 589.0 \mathrm{~nm} \) wavelength

Use the wavelength, \( \lambda = 589.0 \mathrm{~nm} \), and the formula, \( \nu = \frac{c}{\lambda} \). The speed of light, \( c = 3.0 \times 10^8 \mathrm{~m/s} \). Convert the wavelength to meters: \( \lambda = 589.0 \times 10^{-9} \mathrm{~m} \). \( \nu_1 = \frac{3.0 \times 10^8 \mathrm{~m/s}}{589.0 \times 10^{-9} \mathrm{~m}} \)
02

Calculate the frequency for \( 589.6 \mathrm{~nm} \) wavelength

Use the wavelength, \( \lambda = 589.6 \mathrm{~nm} \), and the formula, \( \nu = \frac{c}{\lambda} \). Convert the wavelength to meters: \( \lambda = 589.6 \times 10^{-9} \mathrm{~m} \). \( \nu_2 = \frac{3.0 \times 10^8 \mathrm{~m/s}}{589.6 \times 10^{-9} \mathrm{~m}} \) ##Step 2: Calculate the energies##
03

Calculate the energy for the first frequency

Use the frequency value calculated in step 1 for the \( 589.0 \mathrm{~nm} \) wavelength and the energy formula, \( E = h\cdot\nu \). Planck's constant, \( h = 6.626 \times 10^{-34} \mathrm{~Js} \). \( E_1 = h \cdot \nu_1 \)
04

Calculate the energy for the second frequency

Use the frequency value calculated in step 1 for the \( 589.6 \mathrm{~nm} \) wavelength and the energy formula, \( E = h\cdot\nu \). \( E_2 = h \cdot \nu_2 \) ##Step 3: Convert the energies to kJ/mol##
05

Convert the energy of the first frequency to kJ/mol

Use the energy for the first frequency, \( E_1 \), and convert it to kJ/mol using the conversion factors: \( 1 \mathrm{~J} = 1\times10^{-3} \mathrm{~kJ} \) and \( 1 \mathrm{~mol} = 6.022\times10^{23} \mathrm{~photons} \). \( E_{1, kJ/mol} = E_1 \cdot \frac{1\times10^{-3} \mathrm{~kJ}}{1 \mathrm{~J}} \cdot \frac{1 \mathrm{~mol}}{6.022\times10^{23} \mathrm{~photons}} \)
06

Convert the energy of the second frequency to kJ/mol

Use the energy for the second frequency, \( E_2 \), and convert it to kJ/mol using the same conversion factors. \( E_{2, kJ/mol} = E_2 \cdot \frac{1\times10^{-3} \mathrm{~kJ}}{1 \mathrm{~J}} \cdot \frac{1 \mathrm{~mol}}{6.022\times10^{23} \mathrm{~photons}} \)

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