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Acid Rain Lab Experiment

Page history last edited by PBworks 17 years, 9 months ago

In order to further our understanding of acid rain and see its effects first hand, a lab was completed. We created a mixture similar to that in acid rain by burning sulfur in the air and then adding water.

 

Procedure:

1) Obtain pond water to observe for micro-organisms. Using a microscope, record your observations of the living organisms. It may be helpful to first observe a water sample in a well plate (to see their movement) and then prepare a slide for more careful observation.

2) Cut a piece of skin from an apple and place it in an empty 1000-mL glass bottle. Cut a second piece of apple skin and set it aside for later comparison.

3) Fill a combustion spoon half full of powdered sulfur

4) In a fume hood: Turn on a tap water spigot so that it drips slowly. Light the Bunsen burner. Ignite the sulfur by holding the combustion spoon over the burner flame until you observe a blue flame. Quickly insert the spoon into the bottle and cover as much of the bottle opening as possible with a glass plate.

5) When smoke fills the bottle, remove the spoon. Quickly cover the bottle opening with the glass plate. Extinguish the sulfur fire by holding the spoon under the dripping tap water. Turn off the spigot.

6) Observe the contents of the bottle for approximately three minutes. Record your observations.

7) Add 20 mL of distilled water to the smoke filled bottle. Quickly replace the lid. Take the bottle to your laboratory bench. Swirl its contents carefully for one minute. (This step makes your “acid rain”).

8) Using a pipette, remove some of the solution from the bottle. Add several drops of the solution to the pond water. (We had our pond water in a Petri dish on top of a piece of white paper. Our organisms were visible by eye under these conditions.) Observe for three minutes, and record your observations.

9) Remove the apple skin form the bottle and note any changes in it’s appearance.

10) Using a pipette, place a drop of distilled water on a piece of Ph paper. Record your observations.

11) Using a pipette, place a drop of the liquid from the glass bottle on a piece of Ph paper. Record your observations.

12) Using a pipette, remove some liquid from the glass bottle and put it into a test tube (until approx. 2 cm of the test tube is filled.)

13) Drop a 1-cm length of magnesium ribbon into the test tube. Observe it for at least three minutes before recording your observations.

14) Repeat step twelve for a different test tube.

15) Add two marble chips to the solution in the test tube. Observe for at least three minutes. Record your observations.

16) Remember to wash your hands before leaving the laboratory.

 

 

Analysis:

When the gas produced by burning sulfur dissolved, it made the distilled water extremely acidic. Acid rain has a Ph of 4-4.5; our solution had a Ph of 1.

When we first observed the pond water, we saw three different kinds of micro-organisms: a lot of very small ones that moved slowly, and then two larger kinds that darted around. Under a slide, we closely observed a cyclopoid copepod (one of the two larger kinds).

www.ksu.edu/fishecology/ res_ecology/cyclopoid.JPG

 

When we added the acidic solution to a Petri dish of the pond water, the little guys stopped moving almost immediately, after about 5 seconds. There was one cyclopoid copepod in our dish, and he frantically darted for about 30 seconds, then all of a sudden stopped moving. Obviously, acid rain is very harmful to living things.

 

This was also demonstrated with the apple skin (ours was green). After being exposed to our acidic solution, it overall became a lighter color, and on the edges even became translucent. The white fleshy part of the apple deteriorated, and what remained had hardened.

 

With the magnesium ribbon, bubbles immediatly started forming on the ribbon and floating to the top. There were so many bubbles on the ribbon that they actually pulled the magnesium to the top, and made it float.The color of the magnesium changed from black to a light silvery gray.

 

 

 

 

Bilbliography

Shea, Micheal. Chemistry in the Community. American Chemical Society. Kendall/Hunt Publishing Co. 1993.

Comments (1)

Anonymous said

at 6:04 am on May 20, 2006

This is a great illustration of all your acid rain concepts. Perhaps you could break down your discussion into the same topics as your wiki pages: What is Acid Rain? (reaction of S -->SO3 then SO3 + H2O) Effects on Living Things (pond life, apple) Effects on Architecture (CaCO3). Try to relate to and illustrate all the different parts of your wiki. Any chance of taking some digital photos of your own experiment? You don't have to redo the whole thing, but could take pictures of the highlights.

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