Atomic emission spectra lab answer key

1-8: Atomic Emission Spectra When a sample of gas is excited by applying a large alternating electric field, the gas emits light at certain discrete wavelengths. The intensity and wavelength of the light that is emitted is called the atomic emission spectrum and is unique for each gas. In this lab, you will measure the emission spectra for several elements and molecules, calculate predicted emission lines for hydrogen, and make some observations about the differences in the spectra you observe. 1. Start Virtual ChemLab, select Atomic Theory, and then select Atomic Emission Spectra from the list of assignments. A sample of H2 gas in an electric field will be on the bench and a Spectrometer, a device that collects the light emitted from the gas and separates it by wavelength, will be on the right of the lab table. The hydrogen emission spectra will be in the detector window in the upper right corner along with a graph of Intensity vs. wavelength (). 2. How many distinct lines do you see and what are their colors? 3. Click on the Visible/Full switch to set it to visible to magnify only the visible region of the spectrum (400 to 700 nm). You will see four lines in the spectrum. Click and drag a box in the intensity vs wavelength graph to zoom in. Carefully move your cursor over each line from left to right so that the “finger” coincides with the line, and read the wavelength (in nm) in the x-coordinate field in the bottom right corner of the detector window. Record the wavelengths of the four lines in the visible hydrogen spectrum in the data table below. (Round to whole numbers.) 4. Calculate frequency (in Hz) and energy (in J) of each line and record your results in the data table below (given c = 2.998 × 108 ms-1 and h = 6.626 × 10-34 Js). Show your work for one example calculation of frequency and energy.