Pizza Box Spectrometer Data & Report

Transcription

1 Pizza Box Spectrometer Data & Report Team Name: Members: Section or lab meeting time: Data & Observations: 1. How do you think the grating works? Explain in several sentences. 2. If you were to use your spectroscope to view a source that only emitted two wavelengths of light one and one, what would the spectrum you saw look like? Make a sketch of the top view of your spectroscope and draw colo arrows to indicate the rays of and light and where they would appear in the box and to your eye. Use solid lines to indicate real light rays and dashed or dotted lines to indicate virtual (or imaginary) rays. Make a sketch of how the spectrum of your two lines would appear. 3. Fluorescent lights observations: Do you see a rainbow? What are the colors? Do you see any prominent lines? Does the spectrum appear different depending on whether you open the flap or not?

2 4. Mercury lamp observations: Is there a rainbow or just bright lines? Why do you think the mercury lamp has a different spectra from the fluorescent lights? 5. Moving closer and further away from the Hg lamp: What happens to your spectra? Do the lines get brighter or sharper? Do the lines move? Is the position of the lines the same? What changes occur? 6. How does making the slit larger and smaller affect the spectrum you observe? What is the best width for your spectroscope? What did you base this determination on? Calibrating the spectroscope: 7. Mercury Spectrum Data: Sketch the spectrum you observed below and indicate the approximate numbers on your graph paper: Make a data table of these lines and their corresponding numbers below. Only the 4 bright lines listed in the instructions will have corresponding wavelengths. Line Color Number on your Graph Corresponding Wavelength 8. Using the full sheet of blank graph paper on the next page, plot a graph of the exact wavelength of the four mercury emission lines given above as a function of the numbers on your scale. Note: the variable you measure (or control) should always go on the x-axis. Use a wavelength axis from about 350nm to nm. Using a ruler, draw a best fit straight line through all the points (or as close to all the points as possible). If the points you measu do not fall on or very close to a straight line you should check that you plotted them correctly. If they still do not form a straight line, re-measure the position of the lines using your spectrometer since this graph will determine the accuracy of your spectroscope! Have your instructor initial your graph and check your equation (question 9) before continuing.

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4 9. Determine the equation for the calibration line you drew: Be sure to use the whole line for this and not just two of your data points. The best way is to pick two points near the ends of your best-fit line for determining slope and then extend your line out to the y-axis to find the intercept. Show all work below. Measuring Spectra 10. Record the spectra of any two pure single-atom (monatomic) elements other than mercury and hydrogen (such as Ne, Xe, Kr, Li, etc.). Use colo pens or markers if possible and determine wavelengths using your calibration equation from question 9: Element: Element:

5 11. Repeat the above steps using a polyatomic compound or mixture such as air or CO 2. Record the spectrum in the same way. Polyatomic Compound or Mixture: 12. Hydrogen data. Use the spectroscope to observe and record the visible lines from the hydrogen emission lamp on the graph below (you should see three lines). Using the equation of your line determine the experimental wavelengths of these three visible lines and record them in the table below. Hydrogen Spectrum: Calculated Wavelengths for Hydrogen: Line Color Number on your Graph Calculated Wavelength Observations of metal salts in flame (indicate the color of any 6 salts in the flame): Salt (formula) Flame Color Observed

6 14. Wavelength(s) of the brightest line(s) of sodium and one salt of your choice. Sodium Spectra: Chosen Salt Formula: 15. (see lab instructions there is no "answer" to Q15). 16. Instructors initials for data: 17. Homework: Record the spectrum of 5 different objects from home and include the spectra on the data sheets on the next two pages.

7 Object 1 Observed: Object 2 Observed: Object 3 Observed:

8 Object 4 Observed: Object 5 Observed: Lab Report: Include the answers to lab report questions 1-7 at the end of the experiment (including your excel graph) with this report. Please staple them to the END of the report. You only need to answer question 1-7, there is no "formal write-up" requi. Only one report and set of data sheets are requi per team.