Authentic Assessment Project 4/25/14
Introduction
This task is a summative assessment upon completion of the acids and bases unit. The lab portion will also count
as a lab grade.
The task is broken up in to 6 parts; students may work alone on most of the tasks but must work with a lab partner
on part 4. The task encourages students to get excited about science and use scientific curiosity, facilitates a desire
to know and understand, and to be self-motivated learners. They must analyze a complex situation, perform
calculations, and use their prior knowledge from chemistry class to come up with one of many possible solutions.
They will organize all their information into a plan of action, as well as create and perform a laboratory experiment
based on the real-life scenario.
The Task: Hazmat Situation- http://www.ajc.com/news/news/possible-acid-spill-reported-inlawrenceville/nW4z4/
1. After watching the news clip from the tanker spill just down the street from our school on 3/26/13
brainstorm, using your notes if needed, about the physical and chemical properties of acids and bases.
Generate a list of how acids and bases; respond to each other (acids respond with bases; and bases respond
with acids), feel, taste, and are in aqueous solutions, pH range, litmus paper, phenolthalien, metals,
proteins.
2. You have been chosen; The Hazmat Crew is You
You may work alone or with a partner. You will not be given extra time if your partnership dissolves. If you
choose to work alone you must find another student that is working alone to be your lab partner (part 4). Look
at the “Proposal Worksheet: pages 1 and 2.
 Pretend you are the Hazmat team leader that is called in to clean up the hydrofluoric acid spilled by the
tanker on Duluth Hwy. Come up with at least three relevant and thoughtful questions that you need to
know in order to complete the job.
 Write down your questions and have them approved by the teacher before you proceed. NOTE:
Because there is a vital piece of information you are required to figure out what that is and ask a
question that will provide that information. You will lose points each time you submit your proposal so
be sure your questions are not lacking.
 As you fill in the proposal, it should justify and explain how you are going to safely cleanup this
hazardous spill. You should take every precaution and detail it in your writing. All your calculations
should show your work. You should explain your reasoning, calculations, and defend your conclusions
using data, charts, or reliable sources.
3. Neutralize but don’t die
 First decide on your sodium hydroxide solution (NaOH): Apply what you know about
neutralization of acids and bases to calculate the best molarity and volume of sodium hydroxide
needed to completely react with all the 6M HF that spilled. Assume the density for both solutions
(NaOH and HF) is the same as water.
 Factors to contend with: Getting the sodium hydroxide to the spill site is complicated. Due to traffic
and the location of the spill it is too dangerous to drive a spray truck to deliver the NaOH. You must
decide on another way to apply the NaOH to the spill. One option is to carry the NaOH in six-liter
spray backpacks. The backpacks are plastic and rubber. You may also research other methods, you
must clearly explain this process and the number of crewmembers you will need for the cleanup.
 Hazardous Chemicals: You must contend with the hazardous nature of the NaOH and HF during the
neutralization reaction, as well as the caustic property of sodium hydroxide (refer to chart). Decide
what protective gear you and your crew must wear. See MSDS attached.
 Mention what materials you will bring with you so that you can test and differentiate between the
two clear solutions. Also, identify the test you will perform to show the spill is neutralized.
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Material
Safety Data
Sheet
(MSDS)
Molarity of
NaOH
19M NaOHstrongest
Sodium Hydroxide (Lye) DANGER- causes skin and eye burns (ulcers).
Digestive and respiratory burns.
Cautions: Fire, Corrosive, Health, Reactivity
Diluted in water- fire, reactivity corrosive- health (burn skin), strong fumes
(burns lungs)
Extremely exothermic in water. Heats to above boiling (100°C)
Melts plastic.
6M
Stock supply we have here at school. Corrosive. Reacts vigorously with
water (can reach boiling temperature if solid is added too fast), health- will
cause chemical burns and injury on skin, strong fumes burns lungs.
Exothermic reaction when neutralized with acid. Can melt plastic.
0.1M
Commonly used in lab experiments. Minor skin irritation. Minor fumes.
Slightly exothermic in water and acid.
First Aid
Immediately flush with water for 15 minutes. Get medical aid immediately.
See attached PDF for full MSDS form with all info.
4. Trust But Verify
How will you confirm that the area is safe? Before you and your team can leave it must be established that
your molar solution and volume will react to endpoint. Design and perform an actual titration to assure all
the 6M HCl completely reacts and endpoint is reached. This experiment will be a small scale real scenario;
use measurements based on calculations of a proportionately smaller amount of HF and NaOH. The HF
solution will be given to you but you must make your sodium hydroxide molar solution; calculate the grams
of sodium hydroxide and volume of water you need. Also include a test to determine if HF is a strong acid
or a weak acid. Write up a complete lab report. Include these sections;
background information- write the equation and type of reaction, explain neutralization, and
describe the process of a titration reaction. Describe how you determined the strength of
hydrofluoric acid. Answer the question “Is it a monoprotic acid”. Explain the difference between
monoprotic, diprotic and polyprotic acids. Explain the relationship between conductivity and the
strength of acids and bases. Draw a picture to demonstrate the difference between strong and
weak acids. Predict observations that will occur during this reaction. Include necessary safety
procedures.
Safety- list all safety equipment and cautions for the experiment. Refer to MSDS pdf.)
Materials- (include the grams of NaOH)
Procedures for Titration
Data- HINT: M1V1=M2V2
Conclusions- Justify using data. Explain how you know endpoint is reached.
After the teacher has approved your lab write-up you will do the experiment. Your grade will be based on your
percent error in lab and the number of trials.
5. Comic Relief
Explain your clean-up at the spill cite. Use a 6-8 panel comic strip to describe the scene. Be creative!
6. Clean-Up the Clean-Up
After your hazmat crew has neutralized the danger you must call a front end loader truck to come and
scoop up all the precipitate. Use stoichiometry to determine the mass of the salt (solid precipitate) that will
be produced in this reaction, so that you can tell them and they can chose the correct size of truck to bring
to the spill site.
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