Acid Rain, What a Pain

Name: Audrey Gonzalez

Date of lesson: Fourth and Fifth Week of Acid Rain Unit Lesson

Length of lesson: Four 50 minute periods

Description of the class: Chemistry

Source of the lesson:

• Stanitski, Conrad L., et al. Chemistry in Context: Applying Chemistry to Society. Boston: McGraw Hill. Third Edition
• http://www.ied.edu.hk/apfslt/v5_issue1/fongmw/fongmw6.htm#six
• http://devacaf.caes.uga.edu/main/lessonPlan/acidRainPlantGrowth.pdf
• http://www.scienceacross.org/media/acidrainstatueed.jpg
• http://acidrain2004.tripod.com/sitebuildercontent/sitebuilderpictures/acid_rain_statue.jpg

TEKS addressed:

(3)  Scientific processes. The student uses critical thinking and scientific problem solving to make informed decisions. The student is expected to:

(A)  analyze, review, and critique scientific explanations, including hypotheses and theories, as to their strengths and weaknesses using scientific evidence and information;

(C)  evaluate the impact of research on scientific thought, society, and the environment;

(14)  Science concepts. The student knows the properties and behavior of acids and bases. The student is expected to:

(D)  describe effects of acids and bases on an ecological system.

I. Concept

When sulfur and nitrogen oxides dissolve in water, they become acidic. Rain droplets in clouds absorb them, and these acidic droplets fall in the form of rain, snow, mist, fog, hail, sleet. This contributes to acid rain. Students will do research in the library to see what is acid rain, its affects and preventions.

II. Performance objectives or learner outcomes

Students will be able to:

• Compare and contrast three acid rain maps
• Associate statistics of individual states to a trend in acid rain
• Describe the formation of acid rain verbally and through chemical equation
• Assess what is acid rain, its affects and preventions through unit project

III. Resources, materials and supplies needed

Explore and extend/elaborate per project partner

• Computers

Acid Rain demonstration

• Methyl orange indicator
• 2 Matches
• 2 Glasses
• 2 Watch glasses
• 1 Splint
• Distilled water
• 2 Blue tacks

Plant demonstration

• 4 cups or jars
• distilled water
• pH paper
• vinegar
• baking soda/ammonia
• measuring cups
• stirring spoon
• cuttings of a philodendron plant (1 leaf and small amount of stem)
• cuttings of a begonia or coleus plant (1 leaf and small amount of stem)

IV. Safety Considerations:

· When viewing the acid rain plants, students should be careful not touch the soil as it can be acidic.

· Students should only use the internet for academic purposes only.

V. Supplementary material and handouts:

· Map One – pH of U.S.

· Map Two- Concentration of Nitrogen dioxide

· Map Three- Concentration of Sulfur dioxide

Advanced Preparation for Teacher:

Two weeks before doing the extend/elaborate portion of this lesson, set up acid rain plant demonstration. Repeat instructions to have enough plants for groups of two.

1. Mix 1 teaspoon of vinegar with 2 cups of distilled water.
2. Check the pH with either pH paper or meter, which should be about 4. If it is below pH 4, add a sprinkle of baking soda, or a drop of ammonia, mix, and recheck the pH. If it is above 4, add a drop or two of vinegar, mix, and again recheck the pH.
3. Measure the pH of the distilled water using either pH paper or a garden soil pH testing kit. If the pH is below 7, add about 1/8 teaspoon baking soda or a drop of ammonia, stir well, and check the pH of the water with the pH indicator. If the water is still acidic, repeat the process until pH 7 is reached. Should you accidentally add too much baking soda or ammonia, either start over again or add a drop or two of vinegar, stir, and recheck the pH.
4. Label each cup or jar:

-- water philodendron

-- acid philodendron

-- water begonia (or coleus)

-- acid begonia (or coleus)

5. Pour about a cup of distilled water into the ones labeled "water", and pour a cup of the vinegar mixture into each of the two cups labeled "vinegar".
6. Place a cutting of each plant into each cup, making sure to match the plant type and the label. Cover the stem and the leaf with the liquid. Place the cups where they will receive light.
7. Check the plants every few days to make sure that the plants are still covered by the liquid. Add more liquid as needed.

Five-E Organization

Teacher Does Probing Questions Student Does/Misconceptions

Engage: Day One- Project Day Students will be handed out the three maps. These maps will also be put on the overhead. By now, we have covered everything you need to know to get started on your acid rain project. It is especially important that you incorporate what you learned On the overhead I have three different maps. These are all questions that can be answered through research since you may not know the answers just by looking at these three maps.

What can you conclude about map number one? What can you conclude from map number two? What can you conclude from map number three? What do these three maps mean? How are they relevant to acid rain? How were these numbers determined?

It shows the pH in different parts of the U.S. The northeastern part is the most acidic. The western part seems to be more basic. California has a high nitrogen dioxide concentration. Nitrogen dioxide concentration is also high in the east, east Texas, Arizona, New Mexico etc.. Sulfur dioxide concentration is high in the east, so is Texas. Answer will vary. Answers will vary Answers will vary since students may not know the answers.

Explore: Students will be allowed to do research in the library. They may use the internet and books as resources. They will find information on what is acid rain and statistics on it. They must include statistics and background information regarding the maps. Today is a lab day. You will be doing research in the library. You must address those questions as you do research. These questions should be written on the board so students can copy them into their notebooks. You will need to find statistics on acid rain. Use these three maps as guidance on what to search for in your research; you need to find meaning and explanation from these maps. Tomorrow you will need to turn in a summary of the questions and any statistics you think are important to acid rain. Try to incorporate the concepts you learned about acids/bases in your research, and see how they relate to your acid rain project. We will go over your findings tomorrow in class. When researching, please remember what websites are considered good sources. As students are doing research, walk around monitoring and answering any questions?

What questions will you need to address in your research? What websites and resources will you look at? What type of statistics do you need?

- What do these three maps mean? - How are they relevant to acid rain? - How are these numbers determined? Google scholar, research articles, encyclopedias, government and environmental websites, etc. Contributions to acid rain, damage it causes, what causes acid rain, etc.

Explain: Day Two Have students turn in their summary and statistics. Provide students written feedback that will help them on their final project. Have students present their main findings to the class. Acid rain is produced by sulfur and nitrogen oxides. When sulfur dioxide and nitrogen oxides are released into the atmosphere, they undergo a chemical reaction, and the rain droplets in clouds absorb them. These acidic droplets fall in the form of rain, snow, mist, fog, hail, sleet. This is called acid deposition. The rain samples can be collected to measure the pH. This map shows data collected in 1997. Not all of the acidity is due to acid rain. Carbon dioxide is always present in pure unpolluted rain. CO2 is present in the atmosphere and it dissolves slightly in water. CO2 (g) + H2O(l) à H^+(aq) + HCO3^-(aq) From this equation, we see that H^+ and HCO3^-are formed. Because HCO3^-is a poor H^+ donor, it is not as acidic. At 25°C, the pH is 5.6. Other parts of the states are more acidic because of emissions of sulfur dioxide and nitrogen oxides. Sulfur and nitrogen oxides are not acids themselves. When they dissolve in water, an acid is produced. 1) SO2(g) + H2O(l) à H2SO3(aq) 2) SO3(g) + H2O(l) à H2SO4(aq) 3) H^2SO4(aq) à H^+(aq) + HSO^4-(aq) 4) HSO^4-(aq) à H^+(aq) + SO4^2-(aq) As you can see, H+ keeps dissociating from the acid. The overall equation is: 4) H2SO4(aq) + 2H^+(aq) SO4^2-(aq). 5) 4 NO2(g) + 2 H2O(l) + O2(g) à 4 HNO3(aq) 6) HNO3(aq) à H^+(aq) + NO^3-(aq) We can do a simple demonstration to show that sulfur dioxide does in fact turn an aqueous solution acid. Set up the following demonstration in front of the class: 1. Prepare an indicator solution by dissolving 0.01g methyl orange in 100 ml distilled water. 2. Dilute the indicator solution from 10 ml to 50 ml. Add 10 ml of the resulting indicator solution to each of the 2 glasses. 3. Stick a wooden splint to the inner side of the glass containing 10 ml indicator solution by a blue tack. 4. Stick 2 matches to the inner side of another glass containing 10 ml indicator solution by a blue tack. 5. Ignite the wooden splint and the matches by a glowing splint. 6. Cover the glasses with watch glasses. 7. Swirl the indicator solutions. In basic solutions, (pH > 4.4) the indicator is yellow. In acidic solutions (pH < 3.2), the indicator is red. You found research that coal from coal plants produce sulfur dioxide and nitrogen oxides. Coal has the formula C135H96O9NS. There are so many carbon and hydrogen that large quantities of gaseous CO2 and H2O are produced by the combustion. In combustion reactions, the sulfur from coal combines with oxygen and yields SO2(g) S + O2(g) à SO2(g) This SO2 goes in the atmosphere and reacts with O2 to form SO3. 2 SO2(g) + O2(g) à 2 SO3(g) A lot of automobiles can cause the pH to increase. Automobiles require gasoline to run. Nitrogen in the air is in the form of N2(g). It is stable in this form. However, at high temperatures and pressure, it can react with some elements. There just needs to be a lot of energy for this to happen. The energy can be in the form of high temperatures or a spark, from the internal combustion of an engine. Energy + N2(g) + O2(g) à 2 NO(g) The spark plug from the car causes the gasoline to combust; this makes the automobile move. It also causes nitric oxide to be produced. States with large urban areas, heavy population density, and a lot of automobiles will have higher nitrogen oxide emissions. This same reaction applies to jet engine and the furnaces of coal burning from electrical power plants. Homework: Students will compare/contrast the three graphs in order to analyze their meaning. They may answer as short answer or paragraph form. 1) Why don’t graph two and three have identical concentrations? 2) Explain why high concentrations of either sulfur dioxide or nitrogen dioxide may not reflect the expect pH on map one. 3) How is sulfur dioxide produced? 4) How is nitrogen oxide produced?

What does the pH map mean in terms of acid rain? What does map two and three mean in terms of acid rain. What causes acid rain? What information did you find relevant? Why do certain parts of states have a higher sulfur dioxide and/or nitrogen oxides have a higher pH? How can sulfur and nitrogen oxides be acidic if they do not contain hydrogen? In what ways can the acid rain droplets fall to the earth? What pH range is considered an acid? What pH do you expect pure rain to be? Look at map one, which states do not have acidic rain? What does this mean? Is HCO3^-a weak or strong acid? What does that mean? What causes emission of sulfur dioxide? What causes emission of nitrogen oxides? What is the purpose of an indicator? What do the matches represent? Why do we cover the glasses? Describe the process of what was happening in the glass. How is sulfur and nitrogen oxides formed from coal? What happens in a combustion reaction? Where does the nitrogen come from, and how does it produce nitrogen oxides? From the map, which state(s) have the most nitrogen dioxide concentration? Why?

The rain becomes acidic and causes it to have a lower pH. States with more acid rain have precipitation with a lower pH. The rain is acidic in all parts of the U.S. This may or may not be a result from acid rain. Acid rain is produced by sulfur dioxides and nitrogen dioxides. The maps show where emissions are the greatest in the U.S. Burning of fossil fuels, coal plants, decaying vegetation, automobiles, etc. Answers will vary. Answers will vary. They dissolve in water to make sulfuric or sulfurous acid and nitric acid. Rain, snow, sleet, hail, etc. Anything less than 7 is an acid. pH 7. All have acidic rain. Every state has acidic rain due to acid rain? It is a weak acid. H^+do not dissociate 100%. Coal plants, steel mills. Automobiles and power plants. It changes color if there is a change in pH. It’s the source of sulfur. To keep the gases produced in the glass. The solution was basic to begin with. Striking the match causes SO2 to be produced. SO2 dissolves in the solution and lowers the pH. Answers may vary. Hydrocarbons yield CO2 and H2O. In an incomplete reaction, they form CO. There is nitrogen in the air. It somehow reacts with the hydrocarbons. California, the south part of Arizona, the New England states. They have more cars.

Extend/Elaboration: Day Three Students will be given an overview of the effects of acid rain on the environment and human life. Pass one set of plants to each group you set up two weeks ago and allow students to examine. There are two sets of plants. Two of them are philodendron and the other two are begonia. Two weeks ago, I poured vinegar on two of these plants while the other two had just water poured vinegar, an acid on them. The plants looked identical before they were watered with acid. This is what acid rain can do to plants. Show pictures of what it can do to statues. Continual falling of acid rain on statues can cause them to deteriorate. Their faces are being worn away. Statues made of limestone are acid rain arch nemesis. CaCO3(s) + 2H^+(aq) à Ca^2+(aq) + CO2(g) + H2O(l) This is what is happening chemically to limestone statues. Austin has a lot of limestone. If you remember in the video from the first day, there were pictures of the Barton Springs pool and Mount Bonnell. Acid rain falling in Austin would affect these areas as well. Acid rain falls in bodies of water acidifying it. This can kill fish and other wild life. They cannot withstand the change in pH. There can be indirect effects from the acid rain on Aluminum ions. Al^3+ ions are not very soluble in water, but decreasing the pH can increase solubility. These ions create a thick mucus layer on fish gills causing them to suffocate. The Al^3+ can also react with water to create more H^+ making it more acidic. Al^3+(aq)+ H2O(l) à H^+ [Al(OH0]^2+ (aq) Sometimes the water doesn’t turn acidic such as in the Midwest. There is a lot of argument that forests are being destroyed. Acid rain can have health issues as well. I have given you an introduction of the effects of acid rain. For the remainder of class, you will do more research on the specifics of other effects of acid rain. Make sure to look up information on forests and health related issues. Day Four- Project Day Research on prevention and neutralization of acid rain. You will continue to do research this time, your focus will be on prevention and neutralization of acid rain. Questions to think about:

Just how detrimental is acid rain on the environment and humans? How do these plants look? What do you think could have happened to make two of these plants look like they are dying? What do you think could have caused the statues to look like this? Based on this equation, describe what is happening to limestone statues. Why do you think that is? What’s in the water that can do this? Which is worst: sulfur or nitrogen oxides? What are simple everyday things people can do to prevent acid rain? What can industries do? Are there any alternative solutions?

It can kill plants, animals, make humans sick. One plant type looks healthy while the other looks like it is dying. The dying one looks droopy, yellow, one is shorter than the other. Maybe they weren’t watered or something was poured on them like chemicals, acid rain. Acid rain. Limestone is made of calcium carbonate. It dissolves as it reacts with H^+from acid rain. Something else is causing it to counteract the acidity. Something is neutralizing it. Something that is basic. The nitrate in soil.

Evaluate:

The projects and presentation will be used as the evaluation. It will be graded by a rubric.