Workshop 2 Answer Key

Workshop 2 Answer Key - Workshop#2 Chem 1A 1 Calculate the...

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Unformatted text preview: Workshop #2 Chem 1A 1. Calculate the mass of 0.360 moles of phosphorous (30.97g/mol)? Fall 2010 The answer should have 3 significant figures. 2. How many atoms are in 2.87 g of aluminum (molar mass = 26.98)? The answer should have 3 significant figures. 3. Locate the following examples of electromagnetic radiation on the figure below. Draw a vertical line for each frequency of radiation and label it. a. b. c. d. e. The radiofrequency of 106.7 FM KROQ (106.7 MHz) = 1.067•108 Hz Black light radiation (ie UVA radiation), 315-400 nm = 9.52-7.50•1014 Hz Yellow light, 600 nm = 5.00•1014 Hz The 2.5 GHz radiation of a microwave oven = 2.5•109 Hz Cobalt-60 gamma radiation, approximately 3 x 1020 Hz. Energy in kJ 6.626 x 10-18 6.626 x 10 -14 6.626 x 10-22 6.626 x 10-26 e b c d a 1020 1016 1012 108 Frequency in Hz (s-1) f. Arrange the five examples above in order of increasing wavelength, from shortest to longest e<b<c<d<a g. Arrange the five examples above in order of increasing energy, from lowest to highest a<d<c<b<e 4. Four lines are observed for the line emission spectra in the visible region for hydrogen in a gas discharge tube. Why are all lines seen at once if hydrogen has only one electron? For hydrogen there are four energy transitions in the visible spectrum. All of these energy states are accessed under the gas discharge tube conditions. 5. Calculate the E, ν, and λ of a photon that is emitted from a hydrogen atom when an electron falls from ni = 2 to nf = 1. ( ( ( ) ) ) 6. A single photon has a wavelength of 450 nm. Calculate the energy in 1.5 moles of photons. ( )( ( )( )( )( ) ) 7. The kinetic energy of an electron ejected from a sheet of Mg by a beam of light is 8.17•10-19 J. The frequency of the incident light is 2.127•1015 Hz. Determine the wavelength of the incident light and the work function of Mg. ( )( ) ...
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This note was uploaded on 11/27/2010 for the course CHEM Chem 1A taught by Professor Benhafensteiner during the Fall '10 term at UC Irvine.

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