Submit 7 pages in the following order:
The document must be printed on one side only. −1 mark if double sided print.
Extra page or missing page = −1 mark
It can be typed or legibly handwritten.
The first page must contain at least the following information.
Theory and description of the experiment
This section must not exceed one page!
First line: state clearly your objective. Write the following sentence:
"The objective of the lab is to determine the RH value using the atomic emission of H2"
- Explain in your words the concept of quantized energy based on the Bohr model of the atom.
- Explain how an emission spectrum is obtained. You can use an image if needed.
- The Rydberg equation should be present in your introduction, all the variables defined.
- Finally, describe in one short paragraph the procedure followed in this lab.
- Never copy sentences from the lab manual, use your own words make it short, clear and simple.
One single line at the bottom of the page. writing the following sentence is enough:
«Refer to the SN1 laboratory manual pages 51 to 57.»
Obviously, the complete reference to the lab manual must be present in the section "Reference" at the end of the lab report.Make a clean table using a new lab data sheet:
laboratory data sheet
(lab manual p.57). It must be fully completed.
DO NOT use your lab data sheet (signed by the teacher) for this section
• Indicate at the top of the page the letter (or number) corresponding to the spectroscope used in the lab.
• Complete the "table 2" (lab manual p55-56) using the calibation curfe for your spectroscope.
• Complete the "table 3 your average RH and the %error.
The RH value must be provided with the correct numbers of sig.fig.
No sample calculation in this page. Just data and results!
• Plot the calibration curve for your spectrophotometer: wavelength versus scale reading, using the data in Table 1.
• Give this graph a relevant title, including the spectrophotometer number (or letter).
• You can use Excel to create your own graph or download the following.
EXCEL template
• Enter your data into each of the two fitting models provided (polynomial and power).
• Use the R² value closest to 1 and choose the model that best fits your calibration curve. No need to submit both curves.
• Use the fitting equation to determine the wavelengths of the four spectral lines of the hydrogen atom.
Sample calculations
No need to type the formula, you can hand write (with a pencil) all the calculations
Include a short title (one line) before each calculation.
Perform the required sample calculation for the red emission line only.
(Therefore, no need to write the sample calculations for each of the four emissions)
1- Wavelength determination: Use the “fit” equation of the graph to calculate the red wavelength.
2- Rydberg constant: Calculate the Rydberg constant (RH) for the red emission of hydrogen.
3- % error on RH for the red emission of hydrogen
No sample calculation for the average calculation of RH, just the final value.
However, since it is the final answer, the average value of RH must be submitted with the correct number of significant figures.
Start your conclusion with your RH average value. the RH value SHOULD be given with the correct number of significant figures.
Is this value close enough to the one of the literatures? comment.
What are the difficulties observed and how can this experiment be improved? (other than using a better instrument!!!)
No need to write any sources of error.
"Atomic Emission, pp. 51-57, General Chemistry SN1, Dawson college, W2026 available on MIO (provided by the teacher)
Calculate the Rydberg constant (RH) from the following hydrogen emission spectra experiment:
Electron moving from n = 10 to n = 3 emits a photon in the infrared region at λ = 901.6 nm.
If an excited Be3+ ion with an electron at n = 5 (initial state) absorbs a photon of λ = 290.8 nm:
a. What is the energy of this photon in kJ/mol?
b. To what n level (final) will the electron moves?
(Hint: the Rydberg equation cannot be used here, use the Bohr model of the atom).
To get a marks, all your work must be shown
The page filled in the lab and signed by the teacher.
If you have chosen to write a team lab report, the data sheet (signed by the teacher) of each student participating in the report must be submitted together.
|
RH = Rydberg constant (1.09737 × 107m-1). |
−0.5: Name and date not in ink in the data sheet
−0.5: Equation or formula NOT written on a single line in its own paragraph
−0.5: Equation without a title or without explanation what this equation is used for
−0.5: Wrong sig.fig. for the final answer
−0.5: No unit in the final answer
−0.5: Spectroscope letter missing in the data sheet or the graph
−0.5: Each section must be clearly identified with a title (ex. Introduction, calculations, etc.)
−1.0: Inappropriate graph title (like: wavelength vs. scale reading)
−1.0: Wrong fit used for the calibration curve (chose between polynomial second order or power, consider the one with the highest r2 value)
−1.0: Wrong data point position in the graph
−1.0: Any calculation or number transcription error
−1.0: Double sided printed
−1.0: Extra page, missing page, pages submitted in wrong order
Reminder: This document is a guideline for your lab report. Follow the instructions carefully to ensure proper submission and grading.