lab report chem 120(most basic)

Laurie LeBlanc
Emission of Light
Light is a form of electromagnetic radiation. Electromagnetic energy includes radio waves, microwaves,
infrared rays, visible light, ultraviolet rays, X-rays and gamma rays (see Figure 7.1). Visible light includes
energy that the human eye is capable of detecting. White light is visible light that comes from the sun or
an incandescent light bulb.
400 nanometers
Cosmic and
gamma rays
700 nanometers
Visible to
human eye
Electromagnetic spectrum.
Radio waves
When white light is passed through a prism (diffraction grating and droplets of rain serve the same
purpose), the light is separated into the colors of the rainbow: red, orange, yellow, green, blue, indigo and
violet (ROY G BIV). White light is produced by the combination of all of these individual colors in the
visible spectrum. Red light is the lowest in energy and violet light is the highest.
The current model of the structure of the atom includes the presence of a nucleus surrounded by
electrons. Experimental evidence has led to the hypothesis that electrons in an atom exist at only certain
allowable locations away from the nucleus, corresponding to certain energy levels.
Electrons can absorb energy from a flame or electric discharge, but only in packets that contain the
exact amount of energy necessary to allow the electron to move farther from the nucleus into a higher
energy level. When this occurs, the electron is said to be in an “excited state.” When the electron returns
to a lower energy level, it emits the previously absorbed energy in the form of packets of light called photons,
each carrying an amount of energy equal to the differences between two energy levels.
This phenomenon can be observed as the emission of light from
heated objects (such as the tungsten filament in incandescent light bulbs),
flames (such as the flame tests we will do in the lab) and emission tubes
(as we will observe). An emission tube is a sealed glass tube with metal
plates at both ends. The emission tube is filled with a pure, elemental
gas. By applying a high voltage to the metal plates, the electrons of the
gas can be excited and give off light. The emission tube is similar in design to neon lights (although the glass of neon light is painted to produce
a variety of colors) and fluorescent lights (although the inside of the
glass of fluorescent lights is coated with a fluorescent material).
In an atom, many excited states are possible due to the existence of
a number of energy levels and possible electron transitions. Therefore,
when light is emitted by a large collection of excited atoms, a variety of
energies are released as the electrons return to their lowest energy. When
these photons pass through a prism or a diffraction grating, they produce
a line spectrum, where each line corresponds to photons of a particular
Each element exhibits its own characteristic line spectrum due to
differences in the energy levels of atoms of different elements. When elements are heated in a flame, the characteristic color produced and seen by
figure 7.2
Flame Test for K .
the naked eye is due to the combined effect of the individual spectral lines.
Since hydrogen produces four spectral lines in the visible region – you may
only be able to see three through your diffraction grating – one line is violet, one line is turquoise and one spectral
line is red, the color of the hydrogen emission tube seen by the naked eye is purple (the sum of all the spectral colors).
Experimental Procedure
Part I (to be done in a darkened lab)
White Light Emission
1 Obtain a diffraction slide and flashlight. Observe the white light through the diffraction slide and note the
continuous visible spectrum.
2 Draw the spectrum with colored pencils in your lab notebook.
Emission Tubes
3 Note and draw the color of the hydrogen emission tube at the narrowest part of the tube as it appears to the
naked eye.
4 Look at the tube through a diffraction slide. Note the three spectral lines.
5 Draw their approximate positions and color in your lab notebook. Use black between the emission lines where
there is no color.
6 Label the drawing with the appropriate element name.
7 Repeat the procedure with the emission tubes of mercury, neon and helium.
Chemistry 120
Part II (to be done in a lighted lab)
Elemental Flame Tests
8 Obtain a platinum wire. Be sure that the tip of the wire is coiled in the shape of a small circle. When not in use,
the rod should be kept wire up in your test tube rack. (Care should be taken to avoid bending the wire. It is very
9 In order to thoroughly clean the wire, dip the tip of the wire into a 6 M HCl solution (being careful not to
break it) and heat the wire in the hottest part of the flame of a Bunsen burner until a blue color remains
10 Place 3 to 5 drops of each of the following saturated solutions into individually, labeled test tubes: lithium nitrate,
copper(II) chloride, potassium chloride, barium chloride, strontium nitrate, calcium chloride and sodium chloride.
(You will be observing the characteristic color emitted of the above metal ions when they are burned in a flame.)
11 Dip the loop of the cleaned wire into the first test tube and then hold the loop in the hottest part of the flame.
Note the color of the resulting flame. (It is the INITIAL color that you are looking for.) Draw the flame color
carefully in your lab notebook. Label with the element name.
12 Clean the platinum wire loop with hydrochloric acid, burn it off, and continue observing all known solutions
in the flame. You will use the drawings of your known solutions to identify your unknown solutions.
13 It may be necessary to periodically replace the 6M HCl(aq) if it appears to be contaminated.
14 Obtain samples of two unknown metal ion solutions, which will be assigned to you, and record their codes in
your lab notebook. Perform flame tests on both unknowns, drawing the flame colors of each carefully in your
notebook. Determine the identities of your two unknowns using your observations from the flame tests of the
previous metal ions.
15 Dispose of all waste in the proper waste container. Return your CLEAN platinum wire to your instructor.
Cuyamaca College
Experiment 7 n Emission of Light
**This lab report is to be done entirely in your lab notebook.
1 (a) Explain what causes light to be emitted (on an atomic level) from the emission tubes in Part I.
(b) How does the process differ when light is emitted from the heated aqueous metallic solutions in Part II?
2 (a) Which unknowns were you assigned in Part II?
(b) What were the metals present in your unknowns?
3 Research the phenomenon of light emission and explain three practical applications. To receive credit, you must
explain clearly how each works to the best of your ability. Make your writing understandable; define any technical
terms used. Cite all sources used.
Formal Report Check List
Cover (5%)

Date exp started
Exp name
Abstract (10%)

Only 3 sentences, 1 paragraph
Answers why, how, your results
No pronouns
Background (35%)

5 paragraph essay.
3 Concepts relating to the experiment/lecture, defined, with examples
No comments about the experiment or materials used in the experiment
Not restating the procedure
How much effort was put unto this section
Lab Notebook (30%)

All parts in notebook
Observations do not have graphs, calculations, or opinions
Has a Data Analysis section for graphs, math, etc.
Prelab and Postlab questions as needed.
Did the student have the lab notebook ready for the lab?
Conclusion (20%)

3 major errors inherent in the experiment.
Effects of these errors on the data.
How to prevent, minimize these errors.
: no{{a ~ t:4} f
~ – n• ~
qri-, t-=:=::::::::=- =:::::::==– – — – 7
– l -~
– ~-F–n–~is0s;IJT’o”–~
h_(_~’Y °’-~
kJ ;L

Don't use plagiarized sources. Get Your Custom Essay on
lab report chem 120(most basic)
Just from $13/Page
Order Essay
Calculate the price
Make an order in advance and get the best price
Pages (550 words)
*Price with a welcome 15% discount applied.
Pro tip: If you want to save more money and pay the lowest price, you need to set a more extended deadline.
We know how difficult it is to be a student these days. That's why our prices are one of the most affordable on the market, and there are no hidden fees.

Instead, we offer bonuses, discounts, and free services to make your experience outstanding.
How it works
Receive a 100% original paper that will pass Turnitin from a top essay writing service
step 1
Upload your instructions
Fill out the order form and provide paper details. You can even attach screenshots or add additional instructions later. If something is not clear or missing, the writer will contact you for clarification.
Pro service tips
How to get the most out of your experience with Writall
One writer throughout the entire course
If you like the writer, you can hire them again. Just copy & paste their ID on the order form ("Preferred Writer's ID" field). This way, your vocabulary will be uniform, and the writer will be aware of your needs.
The same paper from different writers
You can order essay or any other work from two different writers to choose the best one or give another version to a friend. This can be done through the add-on "Same paper from another writer."
Copy of sources used by the writer
Our college essay writers work with ScienceDirect and other databases. They can send you articles or materials used in PDF or through screenshots. Just tick the "Copy of sources" field on the order form.
See why 20k+ students have chosen us as their sole writing assistance provider
Check out the latest reviews and opinions submitted by real customers worldwide and make an informed decision.
Business Studies
Customer 454811, January 29th, 2022
Business Studies
great paper!
Customer 454811, January 7th, 2022
Customer 454639, March 30th, 2021
Health Care
Customer 455425, April 22nd, 2023
I got an A on this project after it was review. Thanks
Customer 453877, April 25th, 2020
Thank you!
Customer 455113, March 21st, 2022
IT, Web
Good job
Customer 455223, December 21st, 2021
thank you!!
Customer 454959, February 4th, 2022
Thank you
Customer 454677, April 27th, 2021
Business Studies
Great work!
Customer 455105, May 10th, 2022
Health Care
I got an A and got a good feedback from the instructor. Thanks
Customer 453877, May 20th, 2020
very satisfied
Customer 454099, May 18th, 2020
Customer reviews in total
Current satisfaction rate
3 pages
Average paper length
Customers referred by a friend
15% OFF your first order
Use a coupon FIRST15 and enjoy expert help with any task at the most affordable price.
Claim my 15% OFF Order in Chat
Live Chat+1(978) 822-0999EmailWhatsApp