# Homework Help: Chemistry help

1. Oct 19, 2005

### jewilki1

Sodium vapor lamps are widely used for lighting public areas such as parking lots by emiting 589 nm yellow light.
a. how much energy is emitted by one excited sodium atom when it generates a photon?
b. How much energy is emitted when 1.00 mole of sodium atoms each generate a photon?
Can you help me with this problem. I am studying for a quiz.

How do you work this problem? This comes from problems of the day. We do not get answers or how to work them out. We are just supposed to study them after we work them. Thanks.

2. Oct 20, 2005

### sanitykey

I think the answers may have something to do with the following equations:

$$E=hf$$

Where E is the energy in joules, h is the planck constant of $$6.63 \times 10^{-34}$$ joules per hertz, and f is the frequency of the em-radiation in hertz.

However you have the wavelength of the light not the frequency, but the two are related by:

$$c=f\lambda$$

Where c is the speed of light (about $$3 \times 10^8$$m/s), f is the frequency of the light in hertz and $$\lambda$$ is the wavelength of the light.

If you can find the answer to part a then for part b think about how many sodium atoms are in 1.00 mole.

I hope this helps jewilki1

Last edited: Oct 20, 2005