Question 1.25 (Sixth Edition)

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Steve Magana 2I
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Joined: Fri Sep 28, 2018 12:24 am

Question 1.25 (Sixth Edition)

Postby Steve Magana 2I » Wed Oct 10, 2018 7:26 pm

Question: Sodium vapor lamps, used for public lighting, emit yellow light of wavelength 589 nm. How much energy is emitted by (a) an excited sodium atom when it generates a photon; (b) 5.00 mg of sodium atoms emitting light at this wavelength; (c) 1.00 mol of sodium atoms emitting light at this wavelength?

I'm having difficulty with how to approach this problem. Thank you!

Jerome Mercado 2J
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Joined: Tue Nov 28, 2017 3:02 am

Re: Question 1.25 (Sixth Edition)

Postby Jerome Mercado 2J » Wed Oct 10, 2018 9:08 pm

For part a) you should solve for frequency (v) from the wavelength given. Therefore use the equation which relates wavelength and frequency: c = λν. Using that wavelength use the Energy of the photon equation to solve for energy: E = hv.

For part b) use number of photons per mole constant in substitute for Planck's constant. This will convert it to a useable value in meters (just like h) then multiply it to the energy calculated in part a).

For part c) use the same equation but instead convert 1 mole Na into grams.

Example 1.4 in the book (6th ed.) shows how to do this whole problem.

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