What is the wavelength in nanometer of radiation that has energy content 1×10³KJ/mol?

Physical Chemistry

ScanSolve AI Answer

Answer

1×102 nm1 \times 10^2 \text{ nm}

Step-by-step solution

4 steps

To find the wavelength of radiation given its energy content per mole, we use the relationship between energy, Planck's constant, the speed of light, and Avogadro's number.

Constants:

  • Planck's constant, h=6.626×10−34 J sh = 6.626 \times 10^{-34} \text{ J s}
  • Speed of light, c=3.00×108 m/sc = 3.00 \times 10^8 \text{ m/s}
  • Avogadro's number, NA=6.022×1023 mol−1N_A = 6.022 \times 10^{23} \text{ mol}^{-1}

Given:

  • Energy content, Emol=1×103 kJ/molE_{mol} = 1 \times 10^3 \text{ kJ/mol}
  1. Convert molar energy to Joules per mole

    First, convert the given energy from kilojoules per mole to joules per mole.

    Emol=1×103 kJ/mol×1000 J1 kJE_{mol} = 1 \times 10^3 \text{ kJ/mol} \times \frac{1000 \text{ J}}{1 \text{ kJ}} Emol=1×106 J/molE_{mol} = 1 \times 10^6 \text{ J/mol}
  2. Calculate the energy per photon

    To find the energy of a single photon (EphotonE_{photon}), divide the molar energy by Avogadro's number.

    Ephoton=EmolNAE_{photon} = \frac{E_{mol}}{N_A} Ephoton=1×106 J/mol6.022×1023 mol−1E_{photon} = \frac{1 \times 10^6 \text{ J/mol}}{6.022 \times 10^{23} \text{ mol}^{-1}} Ephoton=1.66057788×10−18 JE_{photon} = 1.66057788 \times 10^{-18} \text{ J}
  3. Calculate the wavelength in meters

    The energy of a photon is related to its wavelength (λ\lambda) by the equation Ephoton=hcλE_{photon} = \frac{hc}{\lambda}. Rearranging this equation to solve for wavelength:

    λ=hcEphoton\lambda = \frac{hc}{E_{photon}} λ=(6.626×10−34 J s)×(3.00×108 m/s)1.66057788×10−18 J\lambda = \frac{(6.626 \times 10^{-34} \text{ J s}) \times (3.00 \times 10^8 \text{ m/s})}{1.66057788 \times 10^{-18} \text{ J}} λ=1.9878×10−25 J m1.66057788×10−18 J\lambda = \frac{1.9878 \times 10^{-25} \text{ J m}}{1.66057788 \times 10^{-18} \text{ J}} λ=1.19704×10−7 m\lambda = 1.19704 \times 10^{-7} \text{ m}
  4. Convert the wavelength to nanometers

    Since 1 m=109 nm1 \text{ m} = 10^9 \text{ nm}, convert the wavelength from meters to nanometers.

    λ=1.19704×10−7 m×109 nm1 m\lambda = 1.19704 \times 10^{-7} \text{ m} \times \frac{10^9 \text{ nm}}{1 \text{ m}} λ=119.704 nm\lambda = 119.704 \text{ nm}

    Rounding to one significant figure, as indicated by the given energy content (1×103 kJ/mol1 \times 10^3 \text{ kJ/mol}):

    λ≈1×102 nm\lambda \approx 1 \times 10^2 \text{ nm}

    The wavelength of the radiation is:

    1×102 nm1 \times 10^2 \text{ nm}
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