Lab 4:  Wednesday.  Analyzing your Mystery Water Sample.


Work in groups on your Mystery Water.  Keep records with photographs, videos, drawings, diagrams, etc.  Set up photo shoots with good light and labels so that you can remember what you were trying to do.





First make general observations: color, turbidity, smell.  Write these out in interesting prose.

At some point I'll come by and help you out with a density test using an cork with a magnet and BBs.  It should take 1 or 2 BBs in this test to distinguish water from salt water mixture, depending on cork size.  If necessary, shave the cork a bit.  I'll do this test individually with each group and give you time to do it for yourselves and figure out for yourselves how to document it.  Video?  Picture?  Diagram?  I'd like you to also write up some prose to explain what this all means and how to interpret the result.

Find PH using strips and digital meter.  Take photos.  Show color of strip against the color key.  Interpret the answer by relating it to the standard examples from the table below.  Be sure that all of you in the group do at least one test strip and argue over what number you get.  Come to a consensus.  Also test distilled water for a baseline. 



Battery acid, hydrofloric acid


Hydrochloric acid in stomach,


Lemon juice, vinegar, gastric acid


Grapefruit and orange juice. Soft drinks.


Tomato juice, acid rain


Acid rain, black coffee, very "soft" tap water


Urine, milk, saliva


"Pure" water,


Baking soda, seawater, eggs


toothpaste (9.9), baking soda


Milk of magnesium, Great Salt Lake (Utah),


Household ammonia


Soapy water


bleaches, oven cleaner, LYE


Liquid drain cleaner, caustic soda,



Take TDS (Total Dissolved Solids) readings with digital meter.  Take photos to demonstrate how TDS numbers don't necessarily reflect turbidity.  For the final write-up research the TDS meter and figure out how they work.  Just a sentence or two for background.  Also test distilled water for a base line.

Exercise in using the chemical test strips.  I'll guide you through this process in class.  Photograph each strip along side the color chart for later comparison.  [See below.]  Do a set of tests for each brand of test strips.  We have JNW and TESTlab brands.  Take good pictures of this for later editing. [See below.]  This is the most important part of the lab. 


            -First test distilled water in order to get a base line.


            -Then test tap water.  See what standard drinking water can look like.


            -Finally test your Mystery Water.  This is the main part of the test.



Example of how you could show this data:

I did this in a few minutes by editing a full picture.  It was not a good full picture.  See below.


I should have given it better, more even, light and been a bit more careful in the setup.

[The test strip is on the left.]

You now have pretty much all the data you can extract with the tools that we have. Start to digest this information.  Look at what other groups are getting so see how you data differs from theirs.  These color tests are pretty subjective.  Get a feel for how to read the colors.  Come up with a profile of your water. 


Each Mystery Sample has 3 primary contaminates in it.  You should hopefully be able to identify at least one of them, if not two.  If you are really lucky and observant, you might figure out all three.


Now that you have a water profile, backwards engineer this profile to come up with a location for your sample.  Where did your sample come from?  Do some internet research.  Try to find a suitable location for your sample and then work from that to tell your story about the water.  How did it get these particular contaminants?  This is where you get to be really creative.  Did it come from a house in Arkansas near a pig farm?  Did it come from the suburbs of Akron, Ohio where they make tires?  Did it come from a town with lead pipes?  Be creative.  Look over the water reports that we have for ideas if you want.


Now, look at water reports (we have several in the classroom and many more can be found on the web) and see what sorts of things they include and start to design your report.  Is there a general structure to a water report?  You don't need to follow that structure, but it might help you figure out what to include and what not to include.  Think about intended audience and what exactly you want to convey.  Improve upon the reports you look at.  Don't just make another boring water report.  Tell a story.  This will require a fit of fictionalization.  Have fun with it.  Figure out the back story.


You don't need a finished product today. Just spitball ideas.  Take notes on everything.  Photograph everything.  Make sure that your photographs are somehow labeled or notated in some way.  Come up with a plan.  Assign tasks to each other.  One person does the graphic editing.  Another designs the tables and diagrams.  Who will embellish the story part?  How is this going to look?  Start to figure this out. 


We'll work more on these tomorrow.





JNW-Direct-Color Chart


TESTlab-Color Chart


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