Chem 434 -Instrumental Analysis Hour Exam 1

7. What is the photoelectric effect and why is it important?Originally the photoelectric effect was associated with the observation that aspark jumped more easily between two metal surfaces when they were illuminated bylight. This experiment was refined to find that when light of certain wavelengths strikesa metal surface it causes electrons to be ejected from the surface. For each metalthere is a different max that causes this effect. If the wavelength of the light is > max noelectrons are ejected, but if the wavelength is < max then electrons are ejected.This is important for two reasons.1. ) This is one of the key experiments that shows that light is quantitized intophotons of energy.2.) This is the basis of the phototube, a common device used inspectrophotometers to detect light.5+8. The 3s3p transition in Na is at about 5893 Å The same Mg transition is at about2798ÅUse the Boltzmann equation (given below) to calculate the fraction of atoms or ions inthe excited state at 2,500C-23The Boltzmann constant (R) is: 1.28x10 J/K(As a reminder, remember that your first step is to convert from wavelength to energy)Assume that you can find the P j from the maximum number of electrons in the P stateand P from the maximum number of electrons in the S state.oNaMg=-105893x10 m-102798x10 mE=hc/ (6.626x10 ×3.00x10 )/5893x10 (6.626x10 ×3.00x10 )/2798x10-193.37x10 J-197.10x10 JBoltzman Eqn-34 8 -10 -34 8 -10-8.81=3e-18.6=3e= .00045 =8.35x10 -9